COMPILE REPORT | Hackers Guide to Visual FoxPro 7.0

ProjectHook

This is the base class for project hooks, which define objects you can attach to a project to let you make things happen while you're working with the project. Every time a project opens, it has the opportunity to create and attach a project hook.

While project hooks have all the usual properties and methods, like Name, Parent, Tag, ReadMethod, and so forth, everything really interesting about project hooks happens in their event methods.

Event	Purpose
Activate	Fires when the project gets focus. Not as useful as we'd like because it doesn't fire while the project is docked.
AfterBuild	Fires when a project's Build method has completed.
BeforeBuild	Fires when a project's Build method is called (whether it's called through the interface or programmatically). Allows you to both make sure certain things happen before the build and change the nature of the build by changing the parameters passed to Build. NODEFAULT halts the build process.
Deactivate	Fires when the project loses focus. Not as useful as we'd like because it doesn't fire while the project is docked.
Destroy	Fires when the project is closed. Lets you turn out the lights as you leave. (Destroy also fires if you release the project hook without closing the project, of course.)
Init	Fires when the project is opened. Lets you do things on the way in. One good thing to do here is give the project hook a reference to the project. (Of course, Init fires if you instantiate a project hook without having it attached to a project, too.) One caution here: The ProjectHook instantiates early in the life of the project, so some project methods (like the source code control CheckIn() and CheckOut()) will not work in the ProjectHook.Init method.
QueryAddFile	Fires when a file is added to the project. Can prevent the file from being added.
QueryModifyFile	Fires when any file in the project is opened for modification (before the appropriate editor opens). Can prevent the editor from opening.
QueryNewFile	Fires when the user chooses to create a new file (before the appropriate editor opens). Can prevent the file from being created.
QueryRemoveFile	Fires when any file is removed from the project. Can prevent the removal of a file.
QueryRunFile	Fires when any file in the project is executed. For reports, read "previewed" for "executed." Can prevent the execution of a file.

Most of these events fire in response to a particular method of the Project COM object. What's most cool is that they fire no matter how that method got called. In VFP 7, three events that don't directly correspond to the Project's method were added: Activate, Deactivate and QueryNewFile.

Project hooks have methods for the "drop" part of OLE drag and drop, and they fire when something is dragged or dropped over the files portion of the project (that is, the white central area, not the gray borders). We can imagine some pretty cool project hooks that let you do additional processing when files are added to the project by drag and drop.

Except for AfterBuild, these methods all have the power to prevent the specified Project method from actually executing—issue NoDefault to do so.

Although you can create project hooks in code (rather than visual) classes, and instantiate and attach those project hooks to open projects, there's no way to make a code class the default project hook for a project. When you try to set ProjectHookLibrary to a PRG, VFP yells at you. You can also run into nasty problems if you have the PRG open while a project is using a class defined within. Since there are no benefits to defining them in code, we suggest you stick with VCX's for project hooks.

Example

  * This simple project hook class simply provides you with * feedback as you work. * Set the Include file for the class as FoxPro.H (in the main * VFP directory) to get access to the project constants used * in BeforeBuild. DEFINE CLASS prjShowMe AS projecthook      Name = "prjShowMe"      *-- A pointer to the project associated with this project     *-- hook.    oProject = .NULL.      PROCEDURE AfterBuild       LPARAMETERS nError       WAIT WINDOW "Finished building project"    ENDPROC      PROCEDURE BeforeBuild         LPARAMETERS cOutputName, nBuildAction, lRebuildAll, ;                   lShowErrors, lBuildNewGuids       LOCAL cBuildType       DO CASE       CASE nBuildAction = BUILDACTION_REBUILD && 1          cBuildType = "rebuild project"       CASE nBuildAction = BUILDACTION_BUILDAPP && 2          cBuildType = "build APP"       CASE nBuildAction = BUILDACTION_BUILDEXE && 3          cBuildType = "build EXE"       CASE nBuildAction = BUILDACTION_BUILDDLL && 4          cBuildType = "build DLL"       ENDCASE         WAIT WINDOW "About to " + cBuildType + " " + ;                   cOutputName NOWAIT    ENDPROC      PROCEDURE QueryRunFile       LPARAMETERS oFile       WAIT WINDOW "Running file "+oFile.Name NOWAIT    ENDPROC      PROCEDURE QueryRemoveFile       LPARAMETERS oFile, cClassName, lDeleteFile         LOCAL cDelete       IF lDeleteFile          cDelete = "Deleting"       ELSE          cDelete = "Removing"       ENDIF         IF EMPTY(cClassName)          WAIT WINDOW cDelete + " file " + oFile.Name NOWAIT       ELSE          WAIT WINDOW "Removing class " + cClassName + ;                      " from " + oFile.Name NOWAIT       ENDIF    ENDPROC      PROCEDURE QueryModifyFile       LPARAMETERS oFile, cClassName         IF EMPTY(cClassName)          WAIT WINDOW "Modifying file " + oFile.Name NOWAIT       ELSE          WAIT WINDOW "Modifying class " + cClassName + ;                      " of " + oFile.Name NOWAIT       ENDIF    ENDPROC      PROCEDURE QueryNewFile      LPARAMETERS cFileType      WAIT WINDOW "Creating a new file of type " ;                  + cFileType NOWAIT    ENDPROC      PROCEDURE QueryAddFile       LPARAMETERS cFileName       WAIT WINDOW "Adding file "+cFileName NOWAIT    ENDPROC      PROCEDURE Init       WAIT WINDOW "Opening project" NOWAIT       IF VARTYPE(_VFP.ActiveProject )= "O"         This.oProject = _VFP.ActiveProject       ENDIF    ENDPROC      PROCEDURE Destroy       WAIT WINDOW "Closing project" NOWAIT    ENDPROC      PROCEDURE Activate       WAIT WINDOW "Activating project" ;                   + This.oProject.Name NOWAIT    ENDPROC      PROCEDURE Deactivate       WAIT WINDOW "Deactivating project" ;                   + This.oProject.Name NOWAIT    ENDPROC   ENDDEFINE