How to avoid overriding a control sequence?

How to avoid overriding a control sequence?

[Nicola]

How do I check in ConTeXt whether a control sequence is already
defined (to avoid redefining it by accident)?

Marginally related to the above, I have tried to use \show, only to
discover, to my surprise, that it gives an error. For example:

\show\NL
\end

Does ConTeXt override some of TeX primitives?

Nicola


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Re: How to avoid overriding a control sequence?

[luigi scarso]

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On Mon, Mar 7, 2016 at 7:40 PM, Nicola <nvitacolonna@gmail.com> wrote:

> How do I check in ConTeXt whether a control sequence is already
> defined (to avoid redefining it by accident)?
>
>
kind of

\ifdefined\writebanner \else \unexpanded\def\writebanner{\writestring}
\fi
?



-- 
luigi

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Re: How to avoid overriding a control sequence?

[Nicola]

On 2016-03-07 18:47:20 +0000, luigi scarso said:

> On Mon, Mar 7, 2016 at 7:40 PM, Nicola <nvitacolonna@gmail.com> wrote:
> How do I check in ConTeXt whether a control sequence is already
> defined (to avoid redefining it by accident)?
> 
> 
> kind of 
> 
> \ifdefined\writebanner \else \unexpanded\def\writebanner{\writestring}     \fi
> ?

That works, thanks!

Nicola


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Re: How to avoid overriding a control sequence?

[Hans Hagen]

On 3/7/2016 7:40 PM, Nicola wrote:
> How do I check in ConTeXt whether a control sequence is already
> defined (to avoid redefining it by accident)?
>
> Marginally related to the above, I have tried to use \show, only to
> discover, to my surprise, that it gives an error. For example:
>
> \show\NL
> \end
>
> Does ConTeXt override some of TeX primitives?

yes, like \month ... but in general if you use uppercase or camelcase 
you're quite safe (there are some math symbols with uppercase but if you 
define your own commands you will probably not use those) ... mechanisms 
like tables that use \NC and so define them local

Hans


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Re: How to avoid overriding a control sequence?

[Nicola]

On 2016-03-07 20:16:45 +0000, Hans Hagen said:

> On 3/7/2016 7:40 PM, Nicola wrote:
>> How do I check in ConTeXt whether a control sequence is already
>> defined (to avoid redefining it by accident)?
>> 
>> Marginally related to the above, I have tried to use \show, only to
>> discover, to my surprise, that it gives an error. For example:
>> 
>> \show\NL
>> \end
>> 
>> Does ConTeXt override some of TeX primitives?
> 
> yes, like \month ... but in general if you use uppercase or camelcase
> you're quite safe (there are some math symbols with uppercase but if you
> define your own commands you will probably not use those) ... mechanisms
> like tables that use \NC and so define them local

I see. Local commands are a good idea. I usually use camelcase, but
since I wanted to define some two-letter sequences, I thought I'd
better be cautious.

Nicola


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