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Tech Note: Detecting the Presence of Externals in a 4D Database
PRODUCT: 4D Server | VERSION: 3.x | PLATFORM: Mac & Win
Published On: January 1, 1996
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Prior to the release of the 4D version 1.5, certain external routines were used to test for whether a 4D external was available or not. Now, with the introduction of the new platform independent extension architecture using the Mac4DX and Win4DX folders, these testing externals may no longer work properly.

This technical note outlines a solution that runs on any platform and works with the old 4D external architecture and the new 4D extensions architecture. Using only 4D code, you can test for the presence of any 4D external in your databases. This includes the 4D productivity and connectivity modules, as well as third party packages.

This note was revised because of a bug when running in compiled mode. A callback to the 4D kernel is necessary for the error processing procedure to run. For this reason a call to IDLE must be inserted in the procedure for it to work in compiled mode.

WIN
http://usdl.4d.com/TN/1996/Windows/TN_1996_01-05_(JAN)/96-01_Detecting_Externals.exe

MAC
http://usdl.4d.com/TN/1996/MacOS/TN_1996_01-05_(JAN)/96-01_Detecting_Externals.hqx