path: root/2022/captions/emacsconf-2022-python--short-hyperlinks-to-python-docs--eduardo-ochs--main.vtt

WEBVTT edited by eduardo
Kind: captions:
Language: en-GB

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Hi! My name is Eduardo Ochs. I'm the author

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of an Emacs package called eev...

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and eev is about taking executable notes

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of everything that you do, and this

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presentation is about how I use this...

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how I finally found a way to take

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executable notes of what the python docs

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say.

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Let me explain that in another way. I've

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try to Learn Python many times, but

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hm, my brain is wired in a weird way, so

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it didn't work... and finally a few

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months ago I found a way of studying

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Python that finally clicked for me.

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The idea is that... well, it's here in

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the title - is a way to create short

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hyperlinks to the

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documentation of python.

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Here's an example.

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This file contains some some chunks

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of code from the Python tutorial and

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some links to the places in which

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I found these chunks of code.

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for example, if I run this link here

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it opens a certain page of the Python

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tutorial in my browser - note that it

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opens the local copy of the

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documentation -

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and if I

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run this link here it opens the source

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in .rst

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of the same page. So the first link opens

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the HTML and this one opens the

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RST. This is useful because in the

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beginning

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I was copying these chunks of code in

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the obvious way - I would simply

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visit the the documentation in HTML and

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I would mark

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a chunk... a snippet of code here and I

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would copy it to my notes.

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And then after a while I

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realized that it was much easier to

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simply go to the RST sources and to copy

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the chunks of code from there... and

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note that these links look quite similar.

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There's one difference here, that is

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this `r' that is prepended to the name

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of the function... the `r' means

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"open the RST"...

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and if I use the suffix `w' it means

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use the documentation on the web instead

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of using the local copy.

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So this one

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opens a local copy

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and this one

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takes a while

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and opens the

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the page of the documentation in the

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site of Python blah blah...

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and this thing here is

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executable in the usual eev sense, that

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we ca... if we type f8 several times here

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the f8s on the lines that start

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with red stars create a target buffer

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here... and in this case it creates a

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target buffer running Python, and if I

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type f8 on these other lines these are

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the lines are sent

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to that REPL.

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But anyway, let me go back.

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Most of the things that I'm going to

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present here are in the tutorial of this...

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package...

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we can go to the source code

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here in the eev directory - it's a file

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called eev-rstdoc.el but the best

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docs are in the tutorial, here...

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and the tutorial also has some

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executable

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chunks... some snippets of python

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code that are executable, but they

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don't have those nice colors... so

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apologies for that.

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We need to run this thing here to make

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everything work.

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This thing will define some functions

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with funny names that I will

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explain later.

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Let me explain something new.

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let's compare all these

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links here. They take this argument

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here and they expand the the argument in

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a certain way. For example this string is

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expanded to this long URL here... note that

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it got a prefix here,

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that's quite long... it got the .html here,

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and then the hash and the anchor here...

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and each one of the functions in the

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pydoc family expands this

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argument in a different way.

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The one that that opens the doc in the

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web uses another prefix -

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this one - and the one that opens the rst

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file ignores the part after the hash

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for technical reasons... I was never

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able to to find a good way to convert

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this hash into a string to search for,

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so to make something that goes to

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the right section in the link to the rst

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doc I have to convert by hand, and by

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trial and error, this thing here into a

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pointer to that section, like

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this one...

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in which the "_numeric-types:"

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is here.

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So all these links here are based on

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expansion, and this is easy to

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understand...

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but suppose that I want to

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create a link like this, or suppose that

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I'm browsing the docs here

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and I just I follow some some links...

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let me do something random here...

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suppose that I decide that this

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section is very interesting. How can I

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create a link to that? I can

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use this pilcrow symbol and the

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"Copy link address",

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and copy the link to

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my notes...

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and then the Python family...

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well, we saw the the functions in the

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Python family have a certain way - have

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several ways of expanding these

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short arguments... and they also have a

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certain way of

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shortening URLs like this one. If I type

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`M-x pdk' the message is this one.

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`pdk' is a mnemonic for

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"Python doc kill", and this

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"kill" means "copy to the kill ring"

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so if I type `M-x pdk' here it

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considers that this thing is a link

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to the python Docs, and it

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shortens this link in a certain way, and

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it kills a short link.

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I can insert the short link with C-y

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(yank)

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and then I can test this link to be sure

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that it points to where I want, and

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then I can delete this thing, and ta-da,

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now I have a short link, and of course I

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can modify this link by adding a suffix

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here...

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and in this case here

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I will have to change the identifier

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to something else...

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but I'm not going to do that now.

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This module of eev comes with three

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families predefined. One is a family that

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points to the the documentation of

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Python itself, another one points the

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documentation of SymPy, that is a program

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for symbolic computation, like for doing

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mathematics equations...

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and the other one points to the

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documentation of MatPlotLib.

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How do these families work?

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Each family has to be defined in two

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parts.

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Remember that

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eev has lots of functions

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like this one... this one

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is the most basic, and it is explained

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here, in this section of the main

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tutorial. This section explains that

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a sexp like this one produces lots of

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functions - produces a family of

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functions - and it does that by producing

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a certain chunk of code and then

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executing this chunk of code... and if we

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add a certain prefix here... `find-' and we

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execute this we can... instead of executing

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that chunk of code we can see what is

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that chunk of code. In the case of `code-c-d'

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it is this. It is a `setq`, several

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`defun's, and some comments here, with

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links to the documentation.

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In the case of rstdoc it's the same.

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We have this function here that defines

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the function in the python family...

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and we can run this to understand what

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this `code-rstdoc' does.

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It creates this temporary buffer here...

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with lots of `defun's, a `code-c-d' here,

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and lots of comments here... and the

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comments include some tests. For example

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we can use these functions here to test

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how the expansion works.

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And

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note that in this buffer here we don't

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have the paths that that this family

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uses. We don't have for example

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the URL that points to the site of

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Python, to the directory that contains

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the reference manual, or whatever... all

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these things are in another part of the

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definition of that family - that is a

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variable.

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If we execute this we go to the

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source code of eev-rstdoc,

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to the parts in which

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this variable is defined...

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and

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for each family we have a variable like

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this,

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whose value is a property

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list with several fields...

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these first fields are very easy to

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understand - they are used in the

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expansion... this one too. And these

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two fields are used in the shrinking -

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in the shortening - and

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this field here

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tells what is the name of the

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killing function

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so the fields of this thing here are

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used

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to generate...

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some fields are used to generate the

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code that appears here, and some fields

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are simply

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read by functions like this one, that

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consults the variable.

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Now the natural question is: how can we

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define new families? Or: how can we change

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a family like this one to point to

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another version of Python?

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There are some template-based functions

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for doing that. They are explained in

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this section of the tutorial...

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where is that?...

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oh God, it's far away...

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here.

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Suppose that we have a package foo, that

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we want to create a family that points

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to the docs

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of that package foo... so, we

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can execute this thing here, and it

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generates this

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this thing from a template.

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If we just want to modify a current

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definition we can run something like

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this - note that the family `:py'

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already exists, and instead of using

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placeholders in some of these

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URLs it will use the current values of

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the fields...

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so we can also use this modify

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existing families.

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Well these are the technical details.

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Now the natural question is: why do I

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want this? This doesn't

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any sense to me! Why should I

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try this?

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And the best answer: is for most people

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this way of using

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executable notes do not make any sense

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at all at first sight...

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so what I'm trying to do is: I'm trying

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to write to these tutorials with

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many examples that are very easy to run,

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and that examine data structures,

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and functions, and test things,

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and so on... so my main argument

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for convincing people to

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test this is: this is trivial to test -

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simply install eev and run this thing

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here, and run the examples, and probably

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you're going to find that this

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tutorial is fun to follow.

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So that's it! =)