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How to test if a procedure is defined ?

Started byPeter Billam <peter@www.pjb.com.au>
First post2016-05-01 11:39 +0000
Last post2016-05-02 05:48 +0000
Articles 5 — 3 participants

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  How to test if a procedure is defined ? Peter Billam <peter@www.pjb.com.au> - 2016-05-01 11:39 +0000
    Re: How to test if a procedure is defined ? Martin Leese <please@see.Web.for.e-mail.INVALID> - 2016-05-01 08:04 -0600
      Re: How to test if a procedure is defined ? Peter Billam <peter@www.pjb.com.au> - 2016-05-02 01:06 +0000
        Re: How to test if a procedure is defined ? luser- -droog <mijoryx@yahoo.com> - 2016-05-01 19:45 -0700
          Re: How to test if a procedure is defined ? Peter Billam <peter@www.pjb.com.au> - 2016-05-02 05:48 +0000

#2557 — How to test if a procedure is defined ?

FromPeter Billam <peter@www.pjb.com.au>
Date2016-05-01 11:39 +0000
SubjectHow to test if a procedure is defined ?
Message-ID<slrnnibqmm.54q.peter@box8.pjb.com.au>
Greetings.  I'm wanting to put together something like perl or lua
'require', by testing if some procedure is defined, and if not
then run-ning the PS 'library' file that will define it.
But I don't see how to test if a procedure is defined. Anything like
  gloop type  or  gloop gcheck
just crashes if gloop is undefined, before type or gcheck get executed.
  /gloop type
just reports nametype, even if  gloop  doesn't exist.
Is there eg: a way to invoke  gloop  within a crash-free sandbox,
eg like  pcall  in lua ?  Any other way to test if it's defined ?

Thanks,  regards,
Peter

-- 

Peter Billam    www.pjb.com.au    www.pjb.com.au/comp/contact.html

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#2558

FromMartin Leese <please@see.Web.for.e-mail.INVALID>
Date2016-05-01 08:04 -0600
Message-ID<ng5271$ufi$1@dont-email.me>
In reply to#2557
Peter Billam wrote:
> Greetings.  I'm wanting to put together something like perl or lua
> 'require', by testing if some procedure is defined, and if not
> then run-ning the PS 'library' file that will define it.
> But I don't see how to test if a procedure is defined. Anything like
>   gloop type  or  gloop gcheck
> just crashes if gloop is undefined, before type or gcheck get executed.
>   /gloop type
> just reports nametype, even if  gloop  doesn't exist.
> Is there eg: a way to invoke  gloop  within a crash-free sandbox,
> eg like  pcall  in lua ?  Any other way to test if it's defined ?

Try:
     yourdict /gloop known
or, if the appropriate dictionary is on the dictionary stack:
     /gloop where

-- 
Regards,
Martin Leese
E-mail: please@see.Web.for.e-mail.INVALID
Web: http://members.tripod.com/martin_leese/

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#2559

FromPeter Billam <peter@www.pjb.com.au>
Date2016-05-02 01:06 +0000
Message-ID<slrnnida14.1og.peter@box8.pjb.com.au>
In reply to#2558
On 2016-05-01, Martin Leese <please@see.Web.for.e-mail.INVALID> wrote:
> Peter Billam wrote:
>> I'm wanting to put together something like perl or lua
>> 'require', by testing if some procedure is defined, and if
>> not then run-ning the PS 'library' file that will define it.
> Try:
>    yourdict /gloop known
> or, if the appropriate dictionary is on the dictionary stack:
>    /gloop where

Yes :-) where is what I needed (never used it before). Concretely:

  /randomrgb where not { (/home/pjb/ps/lib/colours.ps) run } if

Thanks,
Peter

-- 

Peter Billam    www.pjb.com.au    www.pjb.com.au/comp/contact.html

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#2560

Fromluser- -droog <mijoryx@yahoo.com>
Date2016-05-01 19:45 -0700
Message-ID<79ad39d3-c85b-45ad-a352-ec1828161d9b@googlegroups.com>
In reply to#2559
On Sunday, May 1, 2016 at 8:07:57 PM UTC-5, Peter Billam wrote:
> On 2016-05-01, Martin Leese <please@see.Web.for.e-mail.INVALID> wrote:
> > Peter Billam wrote:
> >> I'm wanting to put together something like perl or lua
> >> 'require', by testing if some procedure is defined, and if
> >> not then run-ning the PS 'library' file that will define it.
> > Try:
> >    yourdict /gloop known
> > or, if the appropriate dictionary is on the dictionary stack:
> >    /gloop where
> 
> Yes :-) where is what I needed (never used it before). Concretely:
> 
>   /randomrgb where not { (/home/pjb/ps/lib/colours.ps) run } if
> 

`where` return the dict in the true case, so you probably want 
something more like

  /randomrgb where { pop }{ (/home/pjb/ps/lib/colours.ps) run } ifelse

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#2561

FromPeter Billam <peter@www.pjb.com.au>
Date2016-05-02 05:48 +0000
Message-ID<slrnnidqhp.2s3.peter@box8.pjb.com.au>
In reply to#2560
On 2016-05-02, luser- -droog <mijoryx@yahoo.com> wrote:
>> > Peter Billam wrote:
>>   /randomrgb where not { (/home/pjb/ps/lib/colours.ps) run } if
>
> `where` returns the dict in the true case,

Ah... indeed.

> so you probably want something more like
>  /randomrgb where { pop }{ (/home/pjb/ps/lib/colours.ps) run } ifelse

Thanks :-)
Peter

-- 

Peter Billam    www.pjb.com.au    www.pjb.com.au/comp/contact.html

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