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The LA Fox Developer Newsletter
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Converting
(Con't
from
page 4)
ments.
How Functional Conversion Works
In order to duplicate how a 2.6 screen works, VFP’s designers included the concept of “2.6 READ compatibility mode” in VFP forms. This is not a single setting, but rather is implemented through the use of various properties, events, and objects. A form created in this manner is unlike anything you would (hopefully!) ever consider creating yourself.
Some of the distinctive features of compatibility mode include:
(1)
FormSet
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Every 2.6 screen set is converted into a VFP FormSet, even if the original contained only a single screen. Each screen in the original screen set will be a separate form within this FormSet.
(2)
FormSet Window Type
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Normal VFP form and FormSets have a WindowType of 0-modeless or
1-
modal. FormSets converted from 2.6 have a window type of 2-Read or 3-Read modal. This changes the behavior of the form so that (a) execution pauses at the Show method to mimic a READ command; (b) parameters are passed to the Load method rather than the Init method; and (c) variables created in the Load. m3thoci are visible to the other than being local to theLoa&rnethod. (Nbté that Window Type 2 and 3 cannot be selected for a new form in the Form Designer).
-
(3)
Read snippets
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VFP ForrhSets include several properties and events that correspond to clauses of the 2.8 READ command:
ReadCycle, ReadLock, ReadMouse, ReadSave,
ReadTimeout, ReadActivate,
ReadDeactivate,
ReadShow, Read Valid,
and
ReadWhen.
The converter automatically transfers your 2.6 READ snippets and directives to these locations. In addition, #Section 1 of the Setup code is placed in the Load method of the FormSet, and #Section 2 of the Setup code is placed in the Load method of the first form. (4)
PaaeFrame
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Each Form within the FormSet contains a PageFrame with no tabs. All the objects from the screen are placed on a page in this PageFrame.
(5)
Data environment
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If the original 2.6 screen had an Environment saved with it, a Data Environment is created in the VFP form, along with code to save and restore the position in each table.
(6) .
SPR program file
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For each 2.6 screen, a .SPR program file is created, in addition to the the matching VFP form. This may seem strange, since VFP
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How Visual Conversion Works The Visual conversion option does not implement 2.6 READ Compatibility mode, on the assumption that you want to make your own decisions on how to implement 2.6 snippets and procedures in the new form. It handles the 6 steps above as follows:
(I)
FormSet
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A FormSet is still created, with each screen in the 2.6 screen set appearing as a Jorm within it However, no Method code is placed in the FormSet As a result, if your 2.6 screen set jcontamed only a single screen, you can safely delte the FormSet using the “Remove Form Set menu option on the Form Designer.
(2) EQrnjSet Window
Tyne
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This is 0 or I, depending on whether yur original form was modal.
(3)
Read snippets
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All Snippet code from your original screen is placed in a separate noncompilable .PRG file that you designate at the start of conversion. The code has comments indicating where it would go if you had done a Functional. conversion (e.g., “PROCEDURE ReadValid’). (4)
PaaeFrame
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No PageFrames are placed in the form.
(5)
Data Environment
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If the original 2.6 screen had an Environment saved with it, a Data Environment is created, and code to save and restore the position in each table will be placed in the non-compilable
.
PRG file.
(6) .
SPR oroaram file
A separate .SPR will
not
becreated, so you must remove any lines in the application that called the .SPR, and substitute the appropriate “DO FORM’ command. Code that would have been in the .SPR if you had done a Functional conversion is placed in the non-compilable .PRG file.
Conversion Limitations
During the beta program, many conversion bugs were discovered and corrected. Given the wide
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