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Import the module basShell from 12-05.MDB into your own application. This module is completely self-contained and includes a number of functions that will set up the DDE conversation, do the work or retrieve the information you need, and then terminate the conversation. Because we've hidden all the details of the DDE, you needn't worry about getting all the syntax and parameters correct.

Depending on your needs, call one or more of the wrapper procedures described in Table 12-4. All of these functions are covered in detail in Recipe 12.4.3 (see Table 12-9).

Table 12-4. Procedures in basShell to aid in using DDE between Access and Windows shell

Procedure

Purpose

acbPMCreateGroup

Create a group, given a group name and a pathname for the group file.

acbPMCreateItem

Create a new item, given the group name, the item name, the command line, the default directory, and whether or not to run the application minimized.

acbPMDeleteGroup

Delete a group, given the name of the group to delete.

acbPMDeleteItem

Delete an item from a group, given the name of the group and the name of the item.

acbPMGetGroups

Fill a dynamic array with all the groups.

acbPMGetItems

Fill a dynamic array with all the items for a particular group.

acbPMShowGroup

Show a particular group, given the name of the group and the window mode to use.

acbPMShowMessages

Allow callers outside this module to show or hide messages. Pass in True to show messages, False to hide them (no DDE involved).

Discussion

The Windows shell supports two operations: you can either request information using the DDERequest function (Table 12-5 lists the DDERequest items) or execute actions using the DDEExecute subroutine (Table 12-6 lists the most useful subset of the shell's DDEExecute command-string interface). DDE conversations between Access and the shell involve three steps:

Initiate the conversation.

Perform the necessary tasks.

Terminate the conversation.

Retrieving information from the Windows shell

Table 12-5 describes the two groups of information you can request from Windows. The sample form, frmShell, uses both to fill its two list boxes.

Table 12-5. DDERequest topics for the Windows shell

To retrieve

Program

Topic

Item

Returns

List of groups

PROGMAN, or Folders

PROGMAN, or AppProperties

PROGMAN

List of existing groups, separated with CR/LF pair

List of items in a group

PROGMAN, or Folders

PROGMAN, or AppProperties

List of items in the specified group, separated with CR/LF pair

To retrieve a list of groups from Windows using the Access DDERequest function, you must first initiate a conversation with the PROGMAN program on the PROGMAN topic, requesting information on the PROGMAN item; even if you use the undocumented "Folders" program name and "AppProperties" topic, it still expects you to request information on the PROGMAN item. The DDERequest call returns a carriage-return/line-feed (CR/LF) delimited string of group names. It's up to your code to pull apart the list of groups and place them into whatever data structure is most convenient for you. To simplify this task, you can use the acbPMGetGroups function in basShell. It accepts, as a parameter, a dynamic array to fill in with the list of groups. This function performs the DDERequest for you and calls the private CopyToArray function to break apart the returned stream of groups and fill the array you've sent it. It returns the number of items in the array. Its source code is:

Public Function acbPMGetGroups(avarGroups( ) As Variant)

' Fill a dynamic array with all the Program Manager groups.

Dim lngChannel As Long

Dim strGroups As String

Dim intCount As Integer

On Error GoTo HandleErr

' Most replacement shells will start PROGMAN for you if you attempt

' to start up a DDE conversation with it. That is, you won't need

' to Shell( ) PROGMAN if you're using a replacement shell.

lngChannel = DDEInitiate("PROGMAN", "PROGMAN")

strGroups = DDERequest(lngChannel, "PROGMAN")

intCount = CopyToArray(strGroups,