WEBVTT
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Hi! My name is Eduardo Ochs.
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I'm the author of
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an Emacs package called eev,
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and this talk is about
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a new feature of eev
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called "test blocks".
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Let's start by a demo.
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This is a file in Lua that defines
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these two functions here,
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and if we type <f8> several times here,
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the <f8>s create a Lua REPL here
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and then they send these lines
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to the REPL, where this line here
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loads this file into the REPL,
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and these other lines here
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are tests for these lines.
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There's a lot of information here,
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so let me organize them
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in a more visual way.
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This is our file in Lua.
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Lua sees this thing
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as a multi-line comment,
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but we are going to see it
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as a test block.
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And eev mode is active,
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so <f8> does the right thing.
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These three lines here
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set up the target buffer
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running a Lua REPL.
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You can see the the prompt
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of the REPL here,
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and these lines here
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are sent to the REPL.
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When we type <f8>
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on a line that starts
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with a red star,
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like these lines here,
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what <f8> does is that
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it sends the rest of the line--
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sorry, it executes
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the rest of the line as Lisp.
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So the three <f8>s here
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executes these lines as Lisp,
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and they set up the target buffer here.
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When we type <f8>
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on a line that does not start
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with a red star,
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the <f8> sends the line
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to the target buffer and moves down.
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This line loads this file
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in the REPL, and these lines are tests.
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So we just saw how to use
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an existing test block;
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let's now see how to create
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a new test block.
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We just have to run this:
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M-x ee-insert-test-block -
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or M-x eeit.
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The result depends on the major mode.
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Let's understand that
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by looking at the source code.
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eeit is an alias to this function here,
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and this function is just
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five lines of code plus a docstring...
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and the docstring explains
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that if the major mode is foo-mode,
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then this function tries to call
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a function called ee-insert-test-foo-mode
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if that function exists,
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and that, if that function does not exist,
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then it yields an error.
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And here's an example
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of one such function.
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That's a function that inserts
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a test block in haskell-mode.
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Here we can see two functions like this:
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one for haskell-mode and one for js-mode.
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These functions look quite similar,
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but their effects look quite different.
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To make this comparison here,
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I started by writing--
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by creating seven files,
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each one in a different language.
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Initially, each one of these files
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only had a comment
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with the name of the language...
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so: C, Haskell, Javascript, Org Mode, etc.
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In each one of these files,
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I typed M-x eeit to insert a test block.
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So here we can see that
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these test blocks are different.
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For example, the syntax
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for multi-line comments
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is different depending on the language.
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This block here that selects
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which REPL to run is also different,
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and this line here that tells the REPL
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to load the current file
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is also different,
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depending on the language.
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In some cases, I had to improvise a bit.
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For example, to implement test blocks
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in shell mode, I had to use
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this weird syntax using a here-document.
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In Tcl, I also had to improvise a bit,
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and in some cases,
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I had to improvise a lot.
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For example, in Org Mode,
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there isn't an obvious REPL to run,
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and there isn't an obvious way
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to load the the current Org file
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into the REPL, so the default action
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of M-x eeit in Org Mode
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is just to insert this thing here,
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that we can use to run a shell in a REPL.
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So these functions are quite similar.
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In the beginning,
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I was writing all of them by hand...
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but then I got bored
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and I wrote a function
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to help me write functions like that.
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This function is called find-eeit-links,
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and it creates a temporary buffer,
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and the contents of this temporary buffer
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depends on the major mode. For example,
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if the current mode is python-mode,
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then running this function here
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creates a temporary buffer
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that lets me write the support
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for test blocks in python-mode,
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or rewrite the function
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that supports test blocks
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in python-mode.
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So if I'm in python-mode and I run this,
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I get a temporary buffer like this,
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in which this thing is my template
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for the function. Usually, this string
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is totally wrong,
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I have to rewrite this string,
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but the rest is right.
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You can see python-mode here
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in the name of the function.
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So we have to edit this
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and save that to our ~/.emacs.
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By the way, these things here
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hyperlinks to many different things...
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This Elisp hyperlink here
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points to the source code,
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to the section in which these functions
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are defined. So you can see this here,
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the function that supports C,
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the function for Haskell,
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the function for Javascript, etc...
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and that's it!
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This is a five-minute talk,
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so I can't say much...
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If you want more information,
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or if you want to see real-world examples,
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how I use test blocks, etc. etc.,
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see this page here...
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and I do not have time to explain this
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"By the way" here.
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So that's it! Thanks! =)
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[captions by Eduardo Ochs]
