Microsoft KB Archive/106696

{| = Single Screen Set to Prevent "Too Many READs in Effect" =
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ID: Q106696

2.50 2.50a 2.50b | 2.00 2.50 2.50a 2.50b

WINDOWS              | MS-DOS The information in this article applies to:
 * Microsoft FoxPro for Windows, versions 2.5, 2.5a, 2.5b
 * Microsoft FoxPro for MS-DOS, versions 2.0, 2.5, 2.5a, 2.5b

SUMMARY
If a screen runs another screen, the current number of READs in effect is increased by one. One way to avoid nesting is to have all the screens that call each other in one screen set where only one screen is enabled at a time.

MORE INFORMATION
The following procedure creates a set of screens that can run one another without increasing READ levels by enabling and disabling GETs:

1. Create a new project and name it ONESCRN.

2. Add a new screen to the project and name it ONE.

3. Change the screen type to a window.

4. Name the window One and title the window Screen 1.

5. Create a SAY object with "RDLEVEL" as the expression.

6. Create two push buttons. Enter "Screen 2" and "Quit" as the push button prompts, and enter "X" in the Variable text box.

7. Enter the following code in the Valid Code Snippet:

DO CASE CASE x = 1 SHOW GETS WINDOW one DISABLED SHOW GETS WINDOW two ENABLED CASE x = 2 CLEAR READ ENDCASE

8. Save the screen without saving the environment.

9. Save the screen again as TWO. 10. Change the window name to Two and the window title to Screen 2. 11. Select the push buttons created in step 6.

12. Change the first push button prompt to Screen 1.

13. Change the code in the Valid Code Snippet as follows:

DO CASE CASE y = 1 SHOW GETS WINDOW two DISABLED SHOW GETS WINDOW one ENABLED CASE y = 2 CLEAR READ ENDCASE 14. Name the window Two and title the window Screen 2. 15. Save the screen.

16. Add the screen TWO.SCX to the screen set One in the project.

17. Build the project with the Rebuild Project option.

18. Run the ONE.SPR program.

Note that the RDLEVEL command never returns a value greater than 1, even when you are switching between screens 1 and 2.

For additional information about this topic, please see the following article in the Microsoft Knowledge Base:

ARTICLE-ID: Q106697 TITLE    : How to Prevent "Too Many READs in Effect" Error Message The method described in Q106697 is faster, but requires more memory and more resources. Additional reference words: FoxDos FoxWin 2.00 2.50 2.50a 2.50b errmsg err msg Window Screen switch KBCategory: KBSubcategory: FxenvMemory

Keywords         : kberrmsg FxenvMemory Version          : 2.50 2.50a 2.50b | 2.00 2.50 2.5 Platform         : MS-DOS WINDOWS
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