Remove leading spaces

Remove leading spaces

[Bart C. Wise]

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When a function is called, I would like to remove any leading space.  Then the 
function can control the spacing.  If I don't remove spaces, it then makes a 
difference whether or not I have a space before the function is called.

I would like the output of the following two lines to be equal:
This is a \MyFunction[1] test.
This is a\MyFunction[1] test.

However, they are not because the first line has a space before the function 
call.  

\def\MyFunction{\dosingleempty\doMyFunction}
\def\doMyFunction[#1]{%
    \processaction[#1]%
        [1=>\medspace dog ,%
         2=>\medspace cat ,%
         default=>\ldots]%
}

\starttext
Test1: This is a\MyFunction[1] test.

Test2: This is a \MyFunction[1] test.

Test3: This is a \MyFunction test.

Test4: This is a\MyFunction test.
\stoptext

Is there a way to do this and not cause any side effects?

Thanks,
Bart

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Re: Remove leading spaces

[Wolfgang Schuster]

Am 05.02.2009 um 21:26 schrieb Bart C. Wise:

> When a function is called, I would like to remove any leading space.  
> Then the function can control the spacing. If I don't remove spaces,  
> it then makes a difference whether or not I have a space before the  
> function is called.
>
> Is there a way to do this and not cause any side effects?

You can use \removeunwantedpsaces to remove preceding spaces before
your command and \ignorespaces to gobble spaces after your command.

A faster version of your macro is:

\def\MyFunction
   {\dosingleempty\doMyFunction}

\def\doMyFunction[#1]%
   {\removeunwantedspaces\executeifdefined{myfunction:#1} 
{\getvalue{myfunction:default}}}

\setvalue{myfunction:1}{\medspace dog }
\setvalue{myfunction:2}{\medspace cat }
\setvalue{myfunction:default}{\ldots}

Wolfgang

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Re: Remove leading spaces

[Bart Wise]

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On Thursday 05 February 2009 01:36:16 pm Wolfgang Schuster wrote:
> Am 05.02.2009 um 21:26 schrieb Bart C. Wise:
> > When a function is called, I would like to remove any leading space.
> > Then the function can control the spacing. If I don't remove spaces,
> > it then makes a difference whether or not I have a space before the
> > function is called.
> >
> > Is there a way to do this and not cause any side effects?
>
> You can use \removeunwantedpsaces to remove preceding spaces before
> your command and \ignorespaces to gobble spaces after your command.
>
> A faster version of your macro is:
>
> \def\MyFunction
>    {\dosingleempty\doMyFunction}
>
> \def\doMyFunction[#1]%
>    {\removeunwantedspaces\executeifdefined{myfunction:#1}
> {\getvalue{myfunction:default}}}
>
> \setvalue{myfunction:1}{\medspace dog }
> \setvalue{myfunction:2}{\medspace cat }
> \setvalue{myfunction:default}{\ldots}
>

Thanks Wolfgang for the answer!
And thanks for the coding hints, they are always appreciated!

Bart

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setvalue/setvariable (was: Re: Remove leading spaces)

[Peter Münster]

On Thu, 5 Feb 2009, Wolfgang Schuster wrote:

> A faster version of your macro is:
> 
> \def\MyFunction
>  {\dosingleempty\doMyFunction}
> 
> \def\doMyFunction[#1]%
>  {\removeunwantedspaces\executeifdefined{myfunction:#1}{\getvalue{myfunction:default}}}
> 
> \setvalue{myfunction:1}{\medspace dog }
> \setvalue{myfunction:2}{\medspace cat }
> \setvalue{myfunction:default}{\ldots}

Hello,

I'm working now a lot with \setvariable and \getvariable. What are the
advantages/disadvantages of set/get-value over set/get-variable?

Cheers, Peter

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Re: setvalue/setvariable

[Wolfgang Schuster]

Am 05.02.2009 um 21:55 schrieb Peter Münster:

> On Thu, 5 Feb 2009, Wolfgang Schuster wrote:
>
>> A faster version of your macro is:
>>
>> \def\MyFunction
>> {\dosingleempty\doMyFunction}
>>
>> \def\doMyFunction[#1]%
>> {\removeunwantedspaces\executeifdefined{myfunction:#1} 
>> {\getvalue{myfunction:default}}}
>>
>> \setvalue{myfunction:1}{\medspace dog }
>> \setvalue{myfunction:2}{\medspace cat }
>> \setvalue{myfunction:default}{\ldots}
>
> Hello,
>
> I'm working now a lot with \setvariable and \getvariable. What are the
> advantages/disadvantages of set/get-value over set/get-variable?

It's more a style decision, set/getvariable is at a higher level
than set/getvalue (just wrapper around \csname ... \endcsname) and
they provide a few test macros (doifelsevariable, doifvariable and
doifnotvariable).

Wolfgang

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Re: setvalue/setvariable

[Wolfgang Schuster]

Am 05.02.2009 um 22:08 schrieb Wolfgang Schuster:

> Am 05.02.2009 um 21:55 schrieb Peter Münster:
>
>>> A faster version of your macro is:
>>>
>>> \def\MyFunction
>>> {\dosingleempty\doMyFunction}
>>>
>>> \def\doMyFunction[#1]%
>>> {\removeunwantedspaces\executeifdefined{myfunction:#1} 
>>> {\getvalue{myfunction:default}}}
>>>
>>> \setvalue{myfunction:1}{\medspace dog }
>>> \setvalue{myfunction:2}{\medspace cat }
>>> \setvalue{myfunction:default}{\ldots}
>>
>> I'm working now a lot with \setvariable and \getvariable. What are  
>> the
>> advantages/disadvantages of set/get-value over set/get-variable?
>
> It's more a style decision, set/getvariable is at a higher level
> than set/getvalue (just wrapper around \csname ... \endcsname) and
> they provide a few test macros (doifelsevariable, doifvariable and
> doifnotvariable).

It matters on which level do you work, is your code for the internals
in a module or used by a user.


My example above is on module level and no should use \setvalue to
add his own option for the \MyFunction command, you could now use
low level code and define your own command:

\def\defineMyFunction{\dodoubleargument\dodefineMyFunction}
\def\dodefineMyFunction[#1][#2]%
   {\setvalue{myfunction:#1}{#2}}

\defineMyFunction[1]      [\medspace dog ]
\defineMyFunction[2]      [\medspace cat ]
\defineMyFunction[default][\ldots        ]

You could have also used \setvariables from begin with the following
defintion for the complete macro:

\def\MyFunction{\dosingleempty\doMyFunction}
\def\doMyFunction[#1]%
   {\removeunwantedspaces\getvariabledefault{myvariable}{#1}%
      {\getvariable{myvariable}{default}}}

\setvariables % set all values with one command
   [myvariable]
   [1={\medspace dog },
    2={\medspace cat },
    default={\ldots}]

\setvariable{1}{\medspace dog } % This could be used instead
\setvariable{2}{\medspace cat } % of \setvariables, each value
\setvariable{default}{\ldots}   % is set with a separate command

Wolfgang

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