Kenneth P. Bowman wrote:
> I don't like to write version-dependent code, but with the improved PS
> driver in IDL 7.1 I would like to keep my old workarounds for 24-bit
> color available.
>
> The quantity stored in !VERSION is a string
>
> IDL> help, !version.release
> <Expression> STRING = '7.1'
>
> But this is not simple to convert to a number, because there are
> instances like this
>
> IDL> help, !version.release
> <Expression> STRING = '6.4.1'
>
> Is there an easy way to test whether the version is greater than or equal to 7.1?
>
> Ken Bowman
I use MG_CMP_VERSION, which is tacked onto the end of this post. It
turned out to be more complicated than I thought it should be. This type
of thing is making me think more about the "look before you leap" (LBYL)
philosophy versus the "it's easier to ask forgiveness than permission"
(EAFP) philosophy. Maybe there should be a routine which just tries to
set DECOMPOSED=1 and has an error handler that does the right thing if
that fails?
MG_CMP_VERSION is also part of the dist_tools package which can be
grabbed via the Workbench update mechanism:
URL: http://updates.idldev.com/dist_tools
See the following article if you need help how to use the above URL:
http://michaelgalloy.com/2009/06/03/idl-71-distributing-code .html
There is also convenience routine MG_IDLVERSION that does what is
usually required:
IDL> print, mg_idlversion(require='7.1')
1
Mike
--
www.michaelgalloy.com
Associate Research Scientist
Tech-X Corporation
; docformat = 'rst'
;+
; Compares two version numbers for the more updated number. Returns 0 for
; equal versions, 1 if version1 is later than version2, and -1 if
version1 is
; less than version2. Strings such as 'alpha' and 'beta' may be tacked
on to
; the end of a version, but are compared alphabetically.
;
;
; :Examples:
; For example, 1.2 is later than 1.1.2::
;
; IDL> print, mg_cmp_version('1.2', '1.1.2')
; 1
;
; :Returns:
; -1, 0, or 1
;
; :Params:
; version1 : in, required, type=string
; first version number
; version2 : in, required, type=string
; second version number
;-
function mg_cmp_version, version1, version2
compile_opt strictarr
v1parts = strsplit(version1, '.', /extract, count=v1len)
v2parts = strsplit(version2, '.', /extract, count=v2len)
nparts = v1len > v2len
v1partsValues = lonarr(nparts)
v2partsValues = lonarr(nparts)
v1partsValues[0] = long(v1parts)
v2partsValues[0] = long(v2parts)
for i = 0L, nparts - 1L do begin
if (v1partsValues[i] gt v2partsValues[i]) then return, 1
if (v1partsValues[i] lt v2partsValues[i]) then return, -1
if (i eq nparts - 1L) then begin
nondigitpos1 = stregex(v1parts[i], '[^[:digit:].]')
nondigitpos2 = stregex(v2parts[i], '[^[:digit:].]')
if (nondigitpos1 eq -1L && nondigitpos2 eq -1L) then return, 0
if (nondigitpos1 eq -1L) then return, 1
if (nondigitpos2 eq -1L) then return, -1
case 1 of
v1parts[i] lt v2parts[i]: return, -1
v1parts[i] gt v2parts[i]: return, 1
else : return, 0
endcase
endif
endfor
return, 0
end
; main-level example
v = ['1.2', '1.1.2', '1.1', '1.1alpha', '1.1beta']
colwidth = max(strlen(v)) + 2
print, '', format='(A13, $)'
print, v, format='(5A10)'
for v1 = 0L, n_elements(v) - 1L do begin
print, v[v1] + ' > ', format='(A13, $)'
for v2 = 0L, n_elements(v) - 1L do begin
print, mg_cmp_version(v[v1], v[v2]), $
format='(I10, $)'
endfor
print
endfor
end
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