Henning Hraban Ramm schrieb am 28.09.2019 um 08:53:

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Am 2019-09-27 um 14:58 schrieb Wolfgang Schuster wolfgang.schuster.lists@gmail.com:

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\define\question{44}

\defineexpandable\question{44}

Would it make sense to use a counter or some other TeX construct?

Is it better to use \setvariable(s) for simple values than any \def?

Module: \def etc.

Document/Style: \setvariable(s) because \getvariable works also for unknown keys.

Should I use a \newdimen for every custom measure that I want to use with \dimexpr, e.g.

\def\MyWidth{10mm} or better \newdimen\MyWidth \MyWidth=10mm ?

\definemeasure [MyWIdth] [10mm]

\setupsomething[width=\measure{Mywidth}]

Wolfgang

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

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

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