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Groups > comp.sys.acorn.programmer > #5756

Re: Font problem

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In message <101d047b-eaea-4a5a-8955-bc6e52ad7eac@googlegroups.com>
          jgh@mdfs.net wrote:

>> Partly because about a year I replaced all CLOSE# calls with a function
>> call which checked the handle for zero, closed it if non-zero, and set it
>> to zero.

> A function call? How do you do that?

Like this

DEF PROCclosefile(RETURN H%)
  IF (DEBUG%AND(1<<21)) AND (H%=0) THEN
    *REPORT \R WL: closefile: caller$ HANDLE IS ZERO H%
    *REPORTSTACK
  ENDIF
  LOCAL ERROR
  ON ERROR LOCAL ENDPROC
  CLOSE#H%
  RESTORE ERROR
  H%=0
ENDPROC


> DEFFNclose(chn%)
> IF chn%<>0 THEN CLOSE#chn%:chn%=0
> =some_return_value

> ....won't do what you expect as it only changes the *local* value of
> chn%.

> DEFFNclose(chn%)
> IF chn%<>0 THEN CLOSE#chn%
> =0

> ...with handle%=FNclose(handle%) would do it, though I tend to code
> it inline explictly as: IF hnd%:CLOSE#hnd%:hnd%=0

> However, with the magic of passing-by-reference:

> DEFPROCclose(RETURN chn%)
> IF chn%:CLOSE#chn%:chn%=0
> ENDPROC

> would work, giving you PROCclose(handle%). I'd go further and do:

> DEFPROCclose(RETURN chn%)
> LOCAL tmp%
> IF chn%:tmp%=chn%:chn%=0:CLOSE#tmp%
> ENDPROC

> ...so if an error occurs in the CLOSE#, the handle has already been
> zeroed, so won't cause an attempt to reclose it.


-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

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Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-10 19:25 +0100
  Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-10 19:35 +0100
    Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-10 20:19 +0100
  Re: Font problem Matthew Phillips <spam2011m@yahoo.co.uk> - 2019-05-10 21:21 +0100
  Re: Font problem Harriet Bazley <harriet@bazleyfamily.co.uk> - 2019-05-11 01:20 +0100
  Re: Font problem Paul Sprangers <Paul@sprie.nl> - 2019-05-11 14:28 +0200
    Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-12 20:44 +0100
      Re: Font problem Martin Wuerthner <spamtrap@mw-software.com> - 2019-05-13 19:43 +0200
        Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-13 21:54 +0100
        Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-14 11:57 +0100
      Re: Font problem jgh@mdfs.net - 2019-05-14 21:10 -0700
        Re: Font problem Alan Adams <alan@adamshome.org.uk> - 2019-05-15 10:11 +0100

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