MAKEMSI quickly and reliably creates MSI files in a non-programmatic way\Windows Installer FAQ (the basics)Conditions

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Windows Installer Basics: Conditions

Conditions are "tests" that Windows Installer can perform to determine whether or not to do something, some sources of information that conditions can examine include:

• Standard Windows Installer properties (existence or their value).
• Environment Variables (%SomeVar = "SomeValue").
• Results of "ComponentFind", "FileFind", "ProductFind" or "RegistryRead" commands (via properties).
• Results of your custom actions (via properties).
• Feature states ("is installed") or actions ("will be installed").
• Component states or actions.

See the Windows Installer documentation for more details on what can be tested and how, this page gives you the syntax of conditional statements (Just to be different conditions don't support "formatted strings", real smart).

Some examples of situations which use conditions are:

• launch conditions,
• Determination of which features and components should be installed.
• custom action execution

Its worth having a look at Heath Stewart's "Test your Conditions" blog entry.

WARNING: You need to be aware that some information sources have restrictions on when they can be sequenced, if a condition fails (whether always or sometimes) then you should double check the lifecycle of the items being examined (for example references to the "REMOVE" property can only be made after "InstallValidate" has run).

Predefined Conditions in MAKEMSI Macros

MAKEMSI has predefined some handy macros which can be used to specify some common conditions:

#define? CONDITION_ALREADY_INSTALLED Installed                          ;;Repair, uninstall etc.
#define? CONDITION_INSTALL_ONLY      not Installed                      ;;Doesn't include a repair, uninstall etc!
#define? CONDITION_UNINSTALL_ONLY    Installed and REMOVE~="ALL"        ;;Complete uninstall  - HIGHLY RECOMMENDED at you read the "REMOVE" properties MAKEMSI doco!
#define? CONDITION_EXCEPT_UNINSTALL  not (<$CONDITION_UNINSTALL_ONLY>)  ;;Install, Repair etc (all but complete uninstall)
#define? CONDITION_IS_WIN2000        VersionNT = "500"                  ;;Is OS WIN2000?
#define? CONDITION_IS_WINXP          VersionNT = "501"                  ;;Is OS WINXP?
#define? CONDITION_IS_VISTA          VersionNT = "600"                  ;;Is OS WINDOWS Vista?
#define? CONDITION_IS_WINDOWS_7      VersionNT = "601"                  ;;Is OS WINDOWS Windows7
#define? CONDITION_UI_NONE           UILevel = 2                        ;;Silent Install
#define? CONDITION_UI_BASIC          UILevel = 3
#define? CONDITION_UI_REDUCED        UILevel = 4
#define? CONDITION_UI_FULL           UILevel = 5                        ;;"Normal"
#define? CONDITION_UI_NO_DIALOGS     UILevel <> 5                       ;;Don't bother user with popup dialogs, opening readme files etc.
#define  CONDITION_PER_MACHINE       Version9X or (ALLUSERS = 1)        ;;True if per-machine install.
#define  CONDITION_PER_USER          not (<$CONDITION_PER_MACHINE>)     ;;True if per-user (not per-machine) install.

Use of Macros for Complex Conditions

I recommend that you should create macros for complex conditions (like the above) and use the macros, this way the macros name is self descriptive making it easier to write, read and debug your code (it is obvious what is intended by the definition "CONDITION_UI_FULL").

If you used the macro "IF_REPAIRING_AND_FEATURE_X_IS_BEING_INSTALLED" in 6 places not only does it make it easier to read, but if you are diagnosing a problem and need to fix the condition you will only need to change one place. It is also easier to see if the condition doesn't match the name of the macro (let alone any comments you might have).

The following is a more extreme example of what I recommend, and these could be defined in your personal MAKEMSI configuration file:

;--- Define Feature and Component state queries -----------------------------
#define FeatureIs       (!{$#1} <$INSTALLCOMPARE_{$IS=^EQUAL^}> <$INSTALLSTATE_{$STATE=^LOCAL^}>)  ;;Feature   is already installed
#define FeatureWillBe   (&{$#1} <$INSTALLCOMPARE_{$IS=^EQUAL^}> <$INSTALLSTATE_{$STATE=^LOCAL^}>)  ;;Feature   is being installed
#define ComponentIs     (?{$#1} <$INSTALLCOMPARE_{$IS=^EQUAL^}> <$INSTALLSTATE_{$STATE=^LOCAL^}>)  ;;Component is already installed
#define ComponentWillBe (${$#1} <$INSTALLCOMPARE_{$IS=^EQUAL^}> <$INSTALLSTATE_{$STATE=^LOCAL^}>)  ;;Component is being installed

;--- Define valid "IS" parameter comparison types ---------------------------
#define INSTALLCOMPARE_EQUAL      =
#define INSTALLCOMPARE_NOT_EQUAL  <>

;--- Define valid "STATE" parameter values ----------------------------------
#define INSTALLSTATE_UNKNOWN     -1     ;;No action to be taken on the feature or component.
#define INSTALLSTATE_ADVERTISED   1     ;;Advertised feature. This state is not available for components.
#define INSTALLSTATE_ABSENT       2     ;;Feature or component is not present.
#define INSTALLSTATE_LOCAL        3     ;;Feature or component on the local computer.
#define INSTALLSTATE_SOURCE       4     ;;Feature or component run from the source.

Some examples of comparisons using the above definitions (these must be sequenced after "CostFinalize"):

... Condition=^<$FeatureIs     "COMPLETE" STATE="LOCAL">^    ;;Feature "COMPLETE" is CURRENTLY     installed locally
... Condition=^<$FeatureWillBe "COMPLETE" STATE="LOCAL">^    ;;Feature "COMPLETE" is BEING         installed locally (its not now)
... Condition=^<$FeatureIs     "COMPLETE" IS="NOT_EQUAL">^   ;;Feature "COMPLETE" is CURRENTLY NOT installed locally

Some Example Conditions

The Windows Installer documentation also has some examples, others can be seen throughout this manual, including at:

• The Version9X property.
• The VersionNT property.

Other examples of conditions are:

• %EnvVar = ""
  Tests if the environment variable "EnvVar" is empty (doesn't exist)

• not VersionNT
  Tests if the property "VersionNT" doesn't exist (this is Windows 95-ME)

• VersionNT OR (VersionNT >= 500)
  Tests if the WIN2000, WINXP or later

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