envLib

EnvLib for Visual FoxPro 9

EnvLib is a collection of classes that you can use (and aggregate) to save and restore your environment. The classes save, set, and restore SET, ON, open table, system variable, object properties, and other helpers.

The original version of EnvLib for Visual FoxPro was created by Tom Rettig in July 1995. Tom passed away in February 1996. Since then Visual FoxPro has moved forward significantly. This is an updated version of his original library.

Features

• Over 120 lightweight classes, one for each aspect of the Visual FoxPro environment.
• Objects save, and optionally set, aspects of the VFP environment upon init().
• Objects restore their aspect of the VFP environment upon destroy().
• Therefore facets of the VFP environment are automatically reset when objects go out of scope.
• Objects can be nested at design-time or run-time to group many aspects into one object.
• Objects can be configured at creation-time to not reset upon destroy().

Using EnvLib

To include Envlib in your application, simply call SET PROCEDURE ... ADDITIVE prior to using it.

SET PROCEDURE TO <path>\\EnvLib ADDITIVE

Example — saving the current path

In standard Visual FoxPro, saving and setting SET PATH looks something like this:

LOCAL lcAPath
lcPath= SET( \"path\" )
SET PATH TO newPath  && or SET PATH TO newPath ADDITIVE

* Lots of code here

* Now restore the previously selected work area
SET PATH TO &lcPath   && Do this everywhere you might exit
RETURN

With Envlib, you do this:

LOCAL loAlias  
loAlias= CREATEOBJECT( \"SetPath\", \"newPath\" )
* or loAlias= CREATEOBJECT( \"SetPath\", \"newPath\", \"Additive\" )

* Lots of code here

RETURN

Note you don\’t need to cover every exit point because when lcPath goes out of lexical scope, SET PATH is reset upon its destroy.

Example — saving the current work area

In standard Visual FoxPro, saving the current work area looks something like this:

LOCAL lcAlias
lcAlias= SELECT()

* Lots of code here

* Now restore the previously selected work area
SELECT ( lcAlias )   && Do this everywhere you might exit
RETURN

With Envlib, you do this:

LOCAL loAlias  
loAlias= CREATEOBJECT( \"SaveSelect\" )

* Lots of code here

RETURN

Note you don\’t need to cover every exit point because when loAlias goes out of lexical scope, the work area is reset upon its destroy.

Example — saving the current work area and setting a new work area

LOCAL lcAlias
lcAlias= SELECT()
SELECT Customer

* Lots of code here

* Now restore the previously selected work area
SELECT ( lcAlias )   && Do this everywhere you might exit
RETURN

With Envlib, you do this:

LOCAL loAlias  
loAlias= CREATEOBJECT( \"SetSelect\". \"Customer\" )

* Lots of code here

RETURN

Classes in EnvLib

Abstract Classes

SET Classes

These classes save, set, and restore the various VFP SET commands that have corresponding SET() functions.

ON Classes

These classes save, set, and restore the various VFP ON commands that have corresponding ON() functions.

Workarea Helper Classes

These classes save, set, and restore the various aspects of saving the properties of work areas.

Miscellaneous Helper Classes

These classes save, set, and restore various other things.