Issue with opening PDF file from FilePro

[Brian K. White]

Boaz Bezborodko wrote:
>
> 2.  How do I check if a file can be opened in R/W mode in FP?
>
....
then: form foo{""
then: printer reset 'release the print job so printwizard can take it
then: gosub waitpdf  ' wait for pdf to exist and become writeable
if: pdfok
then: system "start" < tempfile
if: not pdfpk
then: errorbox "Output ("{tempfile{") not created."
....


waitpdf if:
then: cs(4,.1)="0" ; c(3,.0) = "300"  ' c*100msec = timeout (300 = 
30,000 = 30 sec)
wploop if:
then: cs = c/"10" ; show "Waiting" < cs < "for PDF..." ; handle = 
open(tempfile,"wb")
pdfok if: handle ge "0"
then: close handle ; goto ewp
if: c gt "0"
then: c = c - "1" ; sleep "100" ; goto wploop
ewp if:
then: show "" ; return


basically, as per the open() documentation:
"If the file cannot be opened, a negative number is returned."

So, try to open() in write mode, then see if handle is a negative number.
As soon as handle is 0 or greater, close(handle) and proceed to use 
tempfile.

The rest of the stuff is just nice user display and timeout so that it 
won't wait forever if there is some problem and the pdf will never show up.
Don't think that 30 seconds is too long. The user would only ever wait 
that long if the pdf generation failed and the pdf will never show up.
So you don't want to wait forever and force the user to break out 
ungracefully, and you also don't want the "I give up waiting" time to be 
shorter than the worst possible legitimate scenario of a very slow pc on 
a slow network trying to produce a huge report. That could even be 
longer that 30 seconds.

You can even get fancier and return a more informative error message by 
returning the actual error code from handle instead of just waiting for 
handle to be 0 or greater.
ie: when handle is a negative number, it's a negative version of the 
value returned by the OS's open file function. These numbers are defined 
somewhere (msdn web site?) so a -2 may mean file not found or a -5 may 
mean insufficient user priviledges, etc... and add in some abort key 
handling so they can also break out of the wait loop gracefully.

-- 
bkw