FoxPro at development and runtime
You do not want to be using the live data for development so you
must switch between test and live data when you distribute your
application. If you do this manually then there is the danger that
one day you will forget. It's better to switch automatically.
The problem falls into two parts:
- detecting the environment.
- switching to a new data path.
Detecting the environment
At different times I have used four techniques to determine
whether or not the executable is running from within the
development environment. Each has its advantages and drawbacks:
-
Use the
VERSION(2)
function to determine which version of FoxPro is
running. This returns 0 for RunTime, 1 for Standard, and 2 for
Professional.
-
Use the SYS(0) function to get the user's
logon name. SYS(0) returns a string in the form:
user name#machine name
so I use the AT()
function to find the position of the hash then read all the characters
to the left of that position. If the user name is 'GEOFFF' then I
assume that this is me working in development mode. A simple approach
that can give me debugging information in the runtime environment on
any machine.
-
Pass a parameter into the executable. Treat Main.Prg as though it were
a procedure by starting with an
LPARAMETERS
statement and pass the
parameter in by adding it to the command line in the desktop shortcut.
Use the
PCOUNT() function early in Main.Prg to
detect whether or not a parameter
has been supplied. If there's no parameter, I must be in development
mode. If there is a parameter I can either switch to a predetermined
data directory or read the data path from the parameter.
-
Use the FILE() function to see if there is
an INI file in the same directory as the executable. As with the
parameter method above, I can either use the existence of the file to
indicate runtime mode or I can read the path to the data directory
from the ini file.
Whichever technique I have used to detect the environment, I always
set up a global flag so that I can use it throughout the application
to set development options like
SET ESCAPE ON.
Switching to a new path
You can either use the SET PATH command
to tell FoxPro where to find its data files or build a fully-pathed name
for each file explicitly. I prefer to use the
SET PATH technique because it will apply
throughout the application. It can be useful to store other files - such
as an audit log for example - in the data folder too.
There are two techniques to use with the
SET PATH
command. One option is to name the data path explicitly:
IF
glDevMode
SET PATH TO
Data
ELSE
SET PATH TO
j:\LiveData
ENDIF
The other technique is to build (or read) the path as a string and
use macro substitution:
SET PATH TO
&lcDataPath
In both cases remember that you will have to add quotes around the path
if it includes spaces.
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