st: ?bug? in -staticfc-

[Sergiy Radyakin <serjradyakin@gmail.com>]

I am using -staticfc- by Kit Baum, v1.0.1 from 27sep2010 acquired from
SSC with Stata 12.1 and I am getting the following error message:

file __000002.dta could not be opened

after running the following lines (taken from slide 28 of
http://sites.uom.ac.mu/wtochair/attachments/article/3/MRUS4_BC29.slides.pdf):

*********
webuse manufac, clear
staticfc hours L(1/2).caputil lncaputil if tin(1997m1,2008m12), ///
init(48) step(3) gen(cfc4) graph(fig4) replace ///
ti("Three-period-ahead recursive forecasts of hours")
**********

After investigation I see that the following line fails (trace output):
      - postfile `postname' `panvar' `ttype'(start end) `keeppost'
`names' using `"`saving'"', `double' `replace' `every'
      = postfile __00000H  float(start end)   __sah cfc4 cfc4_s cfc4_n
using `"__000002"',  replace

The filename that Stata complains about (__000002) is the argument
saving, which is coming from the following syntax (in line 51):

saving(`rollf', replace)

And in turn the macro rollf is generated earlier in line 46 with a
tempname statement:

tempname rollf enn tval uplim lowlim

It seems to me that the command -tempname- here is used incorrectly
and should be replaced with -tempfile-. Tempname does not create a
fully-qualified temporary filename, so Stata will be attempting to
create a postfile in the current directory, which in my case happened
to be non-writable:

. pwd
C:\Windows\system32

The second consequence of using tempname instead of tempfile is that
the file temporarily created will not be erased after the command
completes.

The manual for -postfile- explicitly recommends using -tempname- as
the generator for the temporary identifier:

" Two names are specified with postfile: postname is a name assigned
to internal memory buffers, and filename is the name of the file to be
created. ...... We recommend that postname always be obtained from
tempname. ..... Using a temporary filename, too, ensures that the file
will be erased if the user presses Break."

I would interpret that as use tempname for obtaining postname (and
_only_ for postname), and use tempfile for obtaining a filename (and
_only_ filename). Which agrees with what  is shown in the help file
for post:
{
  tempname memhold
  tempfile results
  ...
  postfile `memhold' ... using `results'
}

So far as I can see staticfc.ado does not ever call Stata's tempfile,
which is a symptom of a problem.

Current workaround is to change the directory to somewhere where the
user has write access and clean up that folder manually.

Permanent workaround should be something like:
{
  tempfile rollf
  tempname enn tval uplim lowlim
}
instead of
{
  tempname rollf enn tval uplim lowlim
}

I hope this can be fixed.

Best, Sergiy Radyakin
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