Re: Slightly OT: Help needed with asynchronuous function call in JavaScript

[Urs Liska]

Am 24.06.2015 um 07:41 schrieb David Kastrup:
> Urs Liska <address@hidden> writes:
> 
>> Hey all,
>>
>> I'm testing a way to integrate syntax highlighted LilyPond code in a
>> GitBook book. I'm quite happy so far with everything (particularly
>> because I could finally pick up an idea that might eventually lead to
>> colored code examples in the LilyPond manuals).
> 
> Not likely: we are not going to run server-side on-demand colorization.
> Too expensive.

I probably wasn't explicit enough.
At the core of this function is a Python script that calls python-ly
(which can be installed through pip).
What I'm thinking about is integrating this script in the doc build
process, which should definitely be worth the effort and "cost" IMO.

> 
>> But I'm stuck with the problem of getting to the highlighted HTML out of
>> the function and back into the book. The problem is obviously related to
>> asynchronuous function calling, which I simply don't understand well
>> enough (well, I don't really know JavaScript/Node.js).
>>
>> I'd be glad if someone with the relevant experience could have a look at
>> this:
>> https://git.ursliska.de/openlilylib/book/commit/e37710bf6523536aaff7b17ba67b9fcc2718f6da
>>
>> It's somewhat sketchy, not everything expresses my real ideas.
>> I assume that when line 87 tries to read the temporary file this hasn't
>> been written by the called Python script yet.
> 
> I have no clue about JavaScript, but if the Exec call returns a "child",
> you should be able to wait for completion of that child with a function
> called sys.wait or similar.
> 
> It might also be possible to make the output file a "named pipe" before
> starting the program, but that's very system-specific and tricky.  It
> might be easier to tell the program to write its output to standard
> output and find a corresponding JavaScript call that calls a program and
> collects its output.
> 

Johan's suggestion brought me to the right track already. I'll comment
on that as soon as I have something to show.

Urs