| Static Variables in IDL [message #5924] |
Wed, 13 March 1996 00:00  |
santanu
Messages: 8
Registered: March 1996
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Junior Member |
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Hi,
Is there a way to statically allocate variables in IDL ? I would
like to define a static variable in a .pro which is repeatedly called
from an upper level. I am specifically looking for the IDL counterpart
of
static int testint;
I would appreciate any help in this regard,
Thanks
Santanu
santanu@uiuc.edu
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| Re: Static Variables in IDL [message #5994 is a reply to message #5924] |
Thu, 14 March 1996 00:00  |
peter
Messages: 80
Registered: February 1994
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Member |
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Santanu Bhattacharyya (santanu@ux7.cso.uiuc.edu) wrote:
: Hi,
: Is there a way to statically allocate variables in IDL ? I would
: like to define a static variable in a .pro which is repeatedly called
: from an upper level. I am specifically looking for the IDL counterpart
: of
: static int testint;
: I would appreciate any help in this regard,
:
: Thanks
: Santanu
: santanu@uiuc.edu
Place it in a common block. Declare the common block everywhere you
want the variable to be in scope.
Peter
--------------------------------
Peter Webb, HP Labs Medical Dept
E-Mail: peter_webb@hpl.hp.com
Phone: (415) 813-3756
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| Re: Static Variables in IDL [message #5996 is a reply to message #5924] |
Thu, 14 March 1996 00:00 |
rivers
Messages: 228
Registered: March 1991
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Senior Member |
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In article <4i8geg$5fv@vixen.cso.uiuc.edu>, santanu@eehpx22.cen.uiuc.edu
(S Bhattacharyya) writes:
> rivers@cars3.uchicago.edu (Mark Rivers) writes:
>
> Pardon me if I appear a bit obtuse, but I am still a little confused. I am
> under the impression that the common block declaration is equivalent to
> C's global declaration. What I would like to have is a bit of non re-entrant
> code in a standalone function (.pro). I want an IDL .pro that does the
> following::
>
> main()
> {
> for(;;) non_rEntrant();
> }
> non_rEntrant()
> {
> static int block=1;
>
> if (block == 1){
> puts("This is executed only once");
> block=0;
> }
> puts("And this is done over and over again");
> }
>
> The following does exactly the same thing ----------------
>
> pro test
> common SHARE,block
> block=1
>
> repeat begin
> call_procedure,'non_rEntrant'
> endrep until block eq 1
> end
>
> pro non_rEntrant
> common SHARE,block
> if block eq 1 then begin print,'This is executed only once' & block=0 & endif
> print,'And this is done over and over again'
> end
>
> But the two lower level function/pro's are not the same, the
> C version is standalone, how do I make the IDL pro non_rEntrant behave
> in the same way ?
Change your IDL example to the following:
pro test
while (1) call_procedure,'non_rEntrant'
end
pro non_rEntrant
common SHARE,block
if (n_elements(block) eq 0) then begin
print,'This is executed only once'
block=0
endif
print,'And this is done over and over again'
end
The key is n_elements(). If non_rEntrant has never been called then block is
undefined and n_elements(block)=0.
____________________________________________________________
Mark Rivers (312) 702-2279 (office)
CARS (312) 702-9951 (secretary)
Univ. of Chicago (312) 702-5454 (FAX)
5640 S. Ellis Ave. (708) 922-0499 (home)
Chicago, IL 60637 rivers@cars3.uchicago.edu (Internet)
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| Re: Static Variables in IDL [message #5997 is a reply to message #5924] |
Thu, 14 March 1996 00:00 |
santanu
Messages: 8
Registered: March 1996
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Junior Member |
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rivers@cars3.uchicago.edu (Mark Rivers) writes:
> In article <4i7ara$606@vixen.cso.uiuc.edu>, santanu@ux7.cso.uiuc.edu (Santanu Bhattacharyya) writes:
>> Hi,
>> Is there a way to statically allocate variables in IDL ? I would
>> like to define a static variable in a .pro which is repeatedly called
>> from an upper level. I am specifically looking for the IDL counterpart
>> of
>> static int testint;
>>
> Yes, it is easy. Use a common block. Make the name of the common block unique
> enough that you can be sure it won't conflict with common blocks used in other
> procedures.
> common unique_name, testint
> testint = 14
Pardon me if I appear a bit obtuse, but I am still a little confused. I am
under the impression that the common block declaration is equivalent to
C's global declaration. What I would like to have is a bit of non re-entrant
code in a standalone function (.pro). I want an IDL .pro that does the
following::
main()
{
for(;;) non_rEntrant();
}
non_rEntrant()
{
static int block=1;
if (block == 1){
puts("This is executed only once");
block=0;
}
puts("And this is done over and over again");
}
The following does exactly the same thing ----------------
pro test
common SHARE,block
block=1
repeat begin
call_procedure,'non_rEntrant'
endrep until block eq 1
end
pro non_rEntrant
common SHARE,block
if block eq 1 then begin print,'This is executed only once' & block=0 & endif
print,'And this is done over and over again'
end
But the two lower level function/pro's are not the same, the
C version is standalone, how do I make the IDL pro non_rEntrant behave
in the same way ?
I really appreciate the help,
Thanks,
Santanu
santanu@uiuc.edu
> testint will have the value 14 the next time the .pro file is called.
> ____________________________________________________________
> Mark Rivers (312) 702-2279 (office)
> CARS (312) 702-9951 (secretary)
> Univ. of Chicago (312) 702-5454 (FAX)
> 5640 S. Ellis Ave. (708) 922-0499 (home)
> Chicago, IL 60637 rivers@cars3.uchicago.edu (Internet)
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