Programmer 7500

home *** CD-ROM | disk | FTP | other *** search

/ Programmer 7500 / MAX_PROGRAMMERS.iso / PASCAL / OASISS.ZIP / README.1ST next >

Wrap

Text File | 1988-11-22 | 14.7 KB | 368 lines

┌─────────────────────────────────────────┐ │ SAMPLE4 (OASIS Automatic Disk Menu) │ │ EUREKA SOFTWARE ASSOCIATES │ └─────────────────────────────────────────┘ ┌──────────────┐ │ INTRODUCTION │ └──────────────┘ SAMPLE4 is an automatic Disk menu program written in Turbo Pascal using Open Architecture Screen Interface System (OASIS), a powerfull but easy to use development tool including a screen generator. For more on OASIS check the README.OAS file. ┌──────────────┐ │ DESCRIPTION │ └──────────────┘ This example program is quite a useful DOS utility program. With SAMPLE4 any program can be executed directly from the menu just by pointing to it. It can also let you wander across all subdirectories on your disk. It consists of the following files: SAMPLE4.SCS : The format file, containing a single format. SAMPLE4.SCI : The index file to above. SAMPLE4.MSG : Contains all Field Messages. SAMPLE4.PAS : The Turbo Pascal source program. SAMPLE4.EXE : Compiled version of SAMPLE1.PAS. SAMPLE4.ERR : Error message file (not used here) To get started load the above files on you hard disk using DOS copy utility, then type sample4. ┌──────────────────┐ │ TECHNICAL NOTES │ └──────────────────┘ If you are a programmer, novice or expert the following is for you. For a better understanding you are encouraged to consult the README.OAS file and print the SAMPLE4.PAS source file, it's only a few pages long. OASIS 5.0 is also available as a shareware called OASP5E.ARC. (Turbo Pascal 5.0 level). GENERAL STRUCTURE OF PROGRAMS WRIITEN USING OASIS Compiler Option '$V-' This option is required in any SCL program. More details about compiler options can be found in your 'TURBO PASCAL' manual. Without this compiler option specified SCL programs won't compile. USES Statement "USES SCL;" makes SCL accessible from within this program. Main Program The first statement is Select_Format_File('Sample4');. This procedure initializes SCL and all required files. 'Select_Format_File' is the first SCL statement to be executed and it appears only once in any program. Close_Formats; is the last SCL statement. It closes all files and frees the memory space previously used by SCL. Between these two statements, the procedure which processes the format in this program, Handle_first, is called. Format Handling The procedure 'Menu' performs the complete handling of our screen format. The first statement, 'Select_Format('amenu');' loads our format (with the name 'amenu') from the format file into the format stack in memory. 'Display_Format(X_Max DIV 2,Y_Max DIV 2);' will center it on the screen. Then follows the actual format handling loop: REPEAT Handle_Format; ...... ...... UNTIL Format_Done; The same Loop is used to process any format in SCL. The procedure Handle_Format is exited when any of the following occurs: * Before a new field on the format is initialized (=entered) * Before a field is left * Before the format is left (if it is finished) * and, optionally, depending on the format specifications, if a User Function Key has been pressed. The boolean function 'Format_Done' returns FALSE as long as the format has not been finished. The format is considered to be finished if any one of the following conditions occurs: * All mandatory fields are filled in and either 'Escape' was hit or 'Return' was pressed while being in the last field. * The 'Abort' key (F10) is pressed. Apart from reading and writing fields and, the format handling loop is always the same, independent of the number and type of fields on a format. In fact, the above loop can fulfill the handling of any SCL screen format. There is no need to define any logic for Help screens, Display of messages, Input error handling, field check and so on. All this is performed automatically by SCL as part of the Format Specifications which can be modified anytime via SFD. SPECIFIC ATTRIBUTES FOR SAMPLE4 Despite (and maybe especially because of) the fact, that SCL has certainly not been designed to develop DOS utilities, this example demonstrates and highlights its tremendous power and flexibility. The main new features exhibited in this program are: - The 'Execute' and , 'ExecuteDos' routines. - Background processing. - More sophisticated User Interrupt Procedures. This program only uses one Format (screen) and the procedure handling this format is called 'Menu'. The procedures involved in this task are 'Init_Dir_Search', 'Display_Files' and 'Tell_Result'. Apart from this, within the actual Format handling loop, you find a statement which invokes a User Interrupt Procedure ('Handle_Key') in case a User Function Key has been pressed. If the format has been finished (and was not aborted), the procedure 'Do_Work' is executed. The relevant components of the program will be discussed in the following. Init_Dir_Search This procedure initializes the parameters for our Directory search. It sets the boolean variable 'First' to TRUE and the search mask to '*.*' (all files). Note: 'First' is a parameter for the directory search which if TRUE, causes it to initialize a new search, i.e to find the first filename matching the specified mask. Once the first file has been found, it is set to false and subsequent searches will search for the remaining files. Display_Files The first part of this procedure is a REPEAT..UNTIL loop which calls 'Dir'. If 'Dir' returns a result of 0 (zero), meaning that a filename matching the mask was found, the procedure 'Pick_it_if_we_need_it' is called, which determines whether this file is either an executable file or a directory entry. If this is the case, the file name is moved to the first available field and the field count is increased by 1. In order to determine whether the file found should be displayed on the format, we access the SCL variable 'Dta' We exit the REPEAT..UNTIL loop under any one of the following two conditions: either the format is full or there are no more files matching the mask. In the latter case we reinitialize 'Dir' by calling 'Init_Dir_Search' again and we also blank the remaining fields on the format. In every case, we also make a note of the highest field on our format containing a filename entry. Now that's where the real tricky part starts: On this format we want to have two active fields at the same time, one being the field containing the filename to be executed and the other one where the optional parameters can be entered. SCL can only have one active field at a time, therefore we have to cheat somehow. One way to achieve this is to declare all the fields holding filenames (2 to 46) as 'Output' fields and manipulate these fields independent from the normal SCL field processing. This just leaves, what SCL concerns, field 49 as the only cursor accessible field on this format which is consequently active, i.e ready for input, anytime the format is displayed. In order to highlight the currently chosen filename field, we use the 'selected' field attribute. The procedure 'Handle_Keys', which monitors the 'arrow' keys, determines which filename is to be highlighted next and the highlighting itself is performed by the procedure 'New_Field'. Handle_Keys This procedure acts on all User Function Keys defined for this format. In case F9 is pressed, the field holding the currently highlighted filename is deselected and 'Display_files' is called to refill the format. In case the display of the current directory is not yet complete, ('first' is FALSE) the remaining entries are searched to be displayed now, otherwise a new search cycle is initiated to display the first page of file names. In case, one of the 'arrows' or 'Home' or 'End' is pressed we determine the next field (file name) to be highlighted and call 'Next_Field' to do it. The next two keys are only intercepted for user convenience: If 'Escape' is pressed, it is replaced by 'F10' (Abort) which subsequently causes the program to be terminated. If 'Return' is pressed and the parameter field (49) contains spaces this key is replaced by an 'Escape' character, which causes the format to be terminated instantly. The reason for this is that SCL would interpret 'Return' in this case as a command to switch field 49 to 'Edit Mode' and we would have to press 'Return' (or 'Escape') again to finish the format, therefore this manipulation saves the user an additional keystroke. With the exception of the last two cases we want SCL to ignore any other key depression by substituting 'No_Op'. New_Field This procedure is called with two parameters, the field currently highlighted (due to be deselected) and the new field (the one about to be selected, i.e highlighted). This task is performed by the first two statements. Once this is done, 'current field' matches the new field now being highlighted. In the same time frame three more fields need to be updated but instead of being processed here it is treated as a background task because another 'Arrow' key could also already be pressed. In this case priority is given to handle this key first before attempting to update any one of the three fields. By making this task a background job we ensure that it is only done when spare time is available, without delaying any pending keyboard input. In order to notify the Background processing procedure that updates are to be carried out , three boolean flags are set, one for each field to be revised. Do_Work This procedure first fetches the file name from the field currently highlighted. In case of a directory entry it changes the current directory accordingly. If we are dealing with an executable file instead it first builds a string out of the filename (including path) and the parameter entry and then executes this file. Depending on whether it is an '.EXE' file or not, 'Execute' or 'ExecuteDos' is used. The reason for this is that all '.BAT' and some of the '.COM' files (mainly some external DOS commands) require COMMAND.COM to be present while '.EXE' files can be started directly. On return from the previously executed program, a check for successful execution is done and if this is the case a prompt asks the user to press 'Return' to go back to the menu program (The reason for not going directly back is to give him a chance to read the screen content). In case of problems during execution we directly go back to the menu program and 'Tell_Result' displays an appropriate error message. Tell_Result This procedure simply checks whether 'Execute' or 'ExecuteDos' caused a result code indicating an error. If an error occurred the relevant (user defined) error message is displayed in field 50 and a 'beep' is initiated. LP_Background_Task This is assigned as a SCL background Task via the 'LP_Background_Pointer:=@LP_Background_Task;' statement in the main body of the program. It is called by the SCL procedure 'Handle_Format' whenever there is no keyboard input pending and no other work needs to be done. This procedure is used here to update fields 46,47 and 49 after a different filename has been selected by the user. It is based on the simple principle that whenever the procedure is entered all three flags set by 'Next_Field' are checked. If one of these flags is found to be TRUE the pertinent update procedure is performed and the flag is then set to FALSE. The update procedures themselves are clear and easy to understand and therefore not separately described here. NOTICE This document and the information contained herein as well as the described software 'O A S I S' (Open Architecture Screen Interface System) are protected by international copyright law and treaty provisions. Both this documentation and the program are provided strictly on an 'As Is' Basis. There is no warranty, expressed or implied, with respect to the program or the documentation, including but not limited to merchantability and fitness for a particular purpose with respect to defects in the program or the documentation. In no event shall Eureka Software Associates be liable for any loss of profit or any other damage, including but not limited to special, incidental, consequential or other damages. Copyright (C) 1987, 1988 EUREKA SOFTWARE ASSOCIATES Martin Hossfeld Remy Fesnoux 12, Pinewood Green 2344 Yorkshire Iver Heath, Bucks. SLO 0QP Ann Arbor, MI 48104 United Kingdom USA All Rights Reserved. Acknowledgements Turbo Pascal is a registered trademark of Borland International Inc. SFD, SCL, Screen Format Designer, Screen Control Language and Open Architecture Screen Interface System are trademarks of EUREKA SOFTWARE ASSOCIATES. SAMPLE4 is a copyrighted product provided to you under a shareware scheme. SAMPLE4 IS NOT PUBLIC DOMAIN. ┌────────────────────┐ │ The Shareware Idea │ └────────────────────┘ Shareware (sometimes called User supported Software or freeware) attempts to provide useful programs to the PC community at low cost by reducing the dependence on conventional marketing channels. Several software developers have proven that the concept works, to the mutual benefit of the independent program authors and the PC community itself. The user benefits by the availability of low cost software which he can evaluate on his own system before making the decision to purchase it. The author benefits by being able to enter the software market without extensive monetary risks. The user community determines which products succeed based on their true utility, rather than on their marketing achievements. Under this shareware scheme you are allowed and encouraged to copy and distribute the evaluation version of OASIS to your friends, colleagues and wherever you like as long as the following conditions are met: 1. You must distribute it unmodified and complete with all its files. 2. You are not allowed to distribute it commercially for profit. You may only charge for the media and handling.