Re: [NTG-context] passing variables/data between context and lua
On Tue, Oct 08, 2019 at 08:55:30AM -0400, Aditya Mahajan wrote: > So, everytime \setvariables is call, the value of the `set` key is executed. Hello Aditya, this is the key sentence to understand better what "reset" and "set" are good for! I had to read your explanation thrice :-) and run your examples which are really good! Now I have an idea how to use "\setvariables" in a context project. Thank you very much! Rudolf ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___
Re: [NTG-context] passing variables/data between context and lua
On Tue, 8 Oct 2019, Rudolf Bahr wrote:
On Sun, Oct 06, 2019 at 10:44:12PM +0200, Wolfgang Schuster wrote:
While it is true that you're free to choose the name for the keys there are
two keys with a special meaning, these two keys are "reset" and "set". The
value of the "reset" key is used before the values in \setvariables are
stored while "set" is used after the values are stored.
Hello Wolfgang,
thank you very much for your detailed answer and your two examples!
Concerning the two keys with a special meaning, "reset" and "set", remains a
question
to me. For what are they good? Does "reset" clear a data area, namespace
perhaps,
before new data are stored there? If they are keys, what is there value or are
they
commands?
Let's start with a simple example:
\setvariables
[dummy]
[
set={AAA},
reset={BBB},
]
\starttext
Hello World!
\setvariables[dummy][key=value]
\stoptext
When the \setvariables[dummy][key=value] is called, it first executes the
value of `reset` key. So the output of the above is
```
Hello World! BBBAAA
```
Now suppose you want to do some calculations based on the value
of passed key. Let's take a variation of the original question, and define
a macro where we can say
\setvariables[exam][points=5]
\setvariables[exam][points=10]
and we can a macro \totalpoints to show the number of points. (There are
probably better ways to do this than setvariables ...)
Here is one way to define it:
\def\totalpoints{0}
\setvariables
[exam]
[
points=0, % This is important.
set={\edef\totalpoints{\the\numexpr(\totalpoints +
\getvariable{exam}{points})\relax}},
]
\starttext
\setvariables[exam][points=5]
\setvariables[exam][points=10]
The exam has \totalpoints\ points.
\stoptext
So, everytime \setvariables is call, the value of the `set` key is
executed. If I set the value of the `set` key to code that updates the
value of `\totalpoints` macro, then I get the desired behavior.
Writing macros as value of a key can be cumbersome to read. So, we can use
setups:
\def\totalpoints{0}
\startsetups updatepoints
\edef\totalpoints{\the\numexpr(\totalpoints +
\getvariable{exam}{points})\relax}
\stopsetups
\setvariables
[exam]
[
points=0,
set=\directsetup{updatepoints},
]
\starttext
\setvariables[exam][points=5]
\setvariables[exam][points=10]
The exam has \totalpoints\ points.
\stoptext
That's it.
Aditya
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Re: [NTG-context] passing variables/data between context and lua
On Sun, Oct 06, 2019 at 10:44:12PM +0200, Wolfgang Schuster wrote: > While it is true that you're free to choose the name for the keys there are > two keys with a special meaning, these two keys are "reset" and "set". The > value of the "reset" key is used before the values in \setvariables are > stored while "set" is used after the values are stored. Hello Wolfgang, thank you very much for your detailed answer and your two examples! Concerning the two keys with a special meaning, "reset" and "set", remains a question to me. For what are they good? Does "reset" clear a data area, namespace perhaps, before new data are stored there? If they are keys, what is there value or are they commands? Best regards, Rudolf ___ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://context.aanhet.net archive : https://bitbucket.org/phg/context-mirror/commits/ wiki : http://contextgarden.net ___
Re: [NTG-context] passing variables/data between context and lua
Rudolf Bahr schrieb am 06.10.2019 um 07:11:
Hello Wolfgang,
what exactly does the command
"\setvariable{martin}{set}{\directsetup{martin}}"?
Let's start with a simple example where I set a values with the
\setvariables command.
\setvariables
[metadata]
[author=Rudolf Bahr,
date=\currentdate]
\starttext
\getvariable{metadata}{author}\par
\getvariable{metadata}{date}
\stoptext
The main point of the command is that you can choose whatever name you
want for the keys to store the values.
Instead a using a list of values to store in a key-value-method you can
also pass values to single keys with the \setvariable command, e.g.
\setvariable{metatdata}{author}{Rudolf Bahr}.
While it is true that you're free to choose the name for the keys there
are two keys with a special meaning, these two keys are "reset" and
"set". The value of the "reset" key is used before the values in
\setvariables are stored while "set" is used after the values are stored.
I don't understand it. Has it something to do with "Command/datasetvariable"?
No, this is a different mechanism to save values between different
ConTeXt runs which allows one to access values before they are set.
Especially what does "\directsetup"?
When you access the content of a setups-environment you can use the
\setups command (with a trailing s) to pass a list of setups or the
\setup command, both commands allow you to use braces or brackets as
delimiters for the argument. The \directsetup skips the check for the
argument form and allows only braces as delimiter.
\startsetups[example-1]
\startparagraph
First example!
\stopparagraph
\stopsetups
\startsetups[example-2]
\startparagraph
Second example!
\stopparagraph
\stopsetups
\starttext
\setups[example-1,example-2]
\blank
\setups{example-1,example-2}
\blank
\setup[example-1]
\setup[example-2]
\blank
\setup{example-1}
\setup{example-2}
\blank
\directsetup{example-1}
\directsetup{example-2}
\stoptext
Wolfgang
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Re: [NTG-context] passing variables/data between context and lua
> A solution which uses only existing commands in the document.
>
> \startsetups [martin]
> \startlua
> local points = tonumber(\getvariable{martin}{question}) or 0 ;
> points = points * 92 ;
> local answer = 42 ;
> context.setvariable("martin","points",points) ;
> context.setvariable("martin","answer",answer) ;
> \stoplua
> \stopsetups
>
> \setvariable{martin}{set}{\directsetup{martin}}
>
> \starttext
>
> \setvariables [martin] [question=44]
>
> Points: \getvariable{martin}{points}
>
> The answer is \getvariable{martin}{answer}.
>
> \stoptext
Hello Wolfgang,
what exactly does the command
"\setvariable{martin}{set}{\directsetup{martin}}"?
I don't understand it. Has it something to do with "Command/datasetvariable"?
Especially what does "\directsetup"?
Rudolf
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Re: [NTG-context] passing variables/data between context and lua
Thanks for the quick answers. Both suggestions work for me.
@Massi Thanks for the pointer into the cld-mkiv.pdf
@Wolfgang: I have to admit that I don't completely comprehend your solution,
though it
works. Searching around for the commands you use, I came across an older
posting you
answered too:
https://mailman.ntg.nl/pipermail/ntg-context/2012/064326.html
That helps too. However I can find little documentation on the \setvariable/s
commands.
I'll play around with the solution to understand it better.
> \defineexpandable\question{44}
> A solution which uses only existing commands in the document.
>
> \startsetups [martin]
> \startlua
> local points = tonumber(\getvariable{martin}{question}) or 0 ;
>points = points * 92 ;
> local answer = 42 ;
> context.setvariable("martin","points",points) ;
> context.setvariable("martin","answer",answer) ;
> \stoplua
> \stopsetups
>
> \setvariable{martin}{set}{\directsetup{martin}}
>
> \starttext
>
> \setvariables [martin] [question=44]
>
> Points: \getvariable{martin}{points}
>
> The answer is \getvariable{martin}{answer}.
>
> \stoptext
>
> Wolfgang
>
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Re: [NTG-context] passing variables/data between context and lua
Martin Althoff schrieb am 27.09.2019 um 06:59:
Hi, I am trying to pass variables/data between context and lua. Lua would be
used for
calculations on data coming from context.
Unfortunately I can't figure out what to do. The code below doesn't work, but
is there to
illustrate my idea.
Any help would be much appreciated. Thanks, Martin
\define\question{44}
\defineexpandable\question{44}
\starttext
\startluacode
local points = \question * 92
-- do some calculations with points and return to to context
answer=42
\stopluacode
% lots of Text in between
The answer is \answer
\stoptext
A solution which uses only existing commands in the document.
\startsetups [martin]
\startlua
local points = tonumber(\getvariable{martin}{question}) or 0 ;
points = points * 92 ;
local answer = 42 ;
context.setvariable("martin","points",points) ;
context.setvariable("martin","answer",answer) ;
\stoplua
\stopsetups
\setvariable{martin}{set}{\directsetup{martin}}
\starttext
\setvariables [martin] [question=44]
Points: \getvariable{martin}{points}
The answer is \getvariable{martin}{answer}.
\stoptext
Wolfgang
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Re: [NTG-context] passing variables/data between context and lua
\starttext
\define\question{44}
\startluacode
-- see "ConTeXt Lua Documents" manual, §7.4 Looking inside
local question = tokens.getters.macro("question")
-- it's up to you to verify that \question contains a number
-- better using the userdata table for your data
userdata.points = tonumber( question ) * 92
-- do some calculations with points and return to to context
userdata.answer=42
\stopluacode
% lots of Text in between
The answer is \ctxlua{ context(userdata.answer) }. Points are \ctxlua{
context(userdata.points) }.
\stoptext
Best wishes,
Massi
Il 27/09/19 06:59, Martin Althoff ha scritto:
Hi, I am trying to pass variables/data between context and lua. Lua would be
used for
calculations on data coming from context.
Unfortunately I can't figure out what to do. The code below doesn't work, but
is there to
illustrate my idea.
Any help would be much appreciated. Thanks, Martin
\define\question{44}
\starttext
\startluacode
local points = \question * 92
-- do some calculations with points and return to to context
answer=42
\stopluacode
% lots of Text in between
The answer is \answer
\stoptext
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[NTG-context] passing variables/data between context and lua
Hi, I am trying to pass variables/data between context and lua. Lua would be
used for
calculations on data coming from context.
Unfortunately I can't figure out what to do. The code below doesn't work, but
is there to
illustrate my idea.
Any help would be much appreciated. Thanks, Martin
\define\question{44}
\starttext
\startluacode
local points = \question * 92
-- do some calculations with points and return to to context
answer=42
\stopluacode
% lots of Text in between
The answer is \answer
\stoptext
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