Author:halw

Date:2009-01-05T19:34:30.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@152 abb3cda0-5349-4a8f-a601-0c33ac3a8c38

documentation/current/platform-specifics/microsoft-windows/com/eiffelcom-library/eiffelcom-interface-content/interfaces.wiki

@@ -13,7 +13,7 @@ For each interface listed in a type library, the EiffelCOM wizard generates a de
 
 Different languages handle type coercion in different ways. C uses type cast; C++ introduces several type casting mechanisms; Eiffel uses assignment attempt, etc. Every COM interface exposes the <eiffel>QueryInterface</eiffel> function which allows clients to query the COM component for a pointer to another interface. Querying a component for an interface pointer is similar to using an assignment attempt in Eiffel. The Eiffel implementation of the assignment attempt relies on the runtime data. Since changing the Eiffel runtime and the implementation of the assignment attempt was not an option, EiffelCOM introduces a library class [[ref:libraries/com/reference/ecom_queriable_chart|ECOM_QUERIABLE]]  , which has the creation routine 
 <code>
-			make_from_other (other: ECOM_INTERFACE)</code>
+    make_from_other (other: ECOM_INTERFACE)</code>
 
 which queries a COM component internally. Every interface proxy class inherits from [[ref:libraries/com/reference/ecom_queriable_chart|ECOM_QUERIABLE]] . The one difference between this mechanism versus using assignment attempt is that upon failure an exception will be raised. An assignment attempt that fails simply returns <code>Void</code>. 
 

documentation/current/platform-specifics/microsoft-windows/com/eiffelcom-library/eiffelcom-interface-content/structures.wiki

@@ -13,55 +13,55 @@ ECOM_EXCEPTION provides support for triggering and catching exceptions. Accordin
 
 The status code is mapped by the EiffelCOM runtime to Eiffel exceptions. To raise COM-specific exceptions, the class ECOM_EXCEPTION provides the feature <eiffel>trigger</eiffel>: 
 <code>
-	trigger (code: INTEGER)
-      		-- Raise exception with code `code'.
-      		-- See class ECOM_EXCEPTION_CODES for possible values.
-		</code>
+    trigger (code: INTEGER)
+            -- Raise exception with code `code'.
+            -- See class ECOM_EXCEPTION_CODES for possible values.
+</code>
 
 The class also has several features that help analyzing exceptions and error codes received from the COM runtime. 
 <code>
-	hresult: INTEGER
-       			-- Original HRESULT.
-   		require
-       			applicable: is_developer_exception
+    hresult: INTEGER
+            -- Original HRESULT.
+        require
+            applicable: is_developer_exception
 
-	hresult_code: INTEGER
-       			-- Status code.
-   		require
-       			applicable: is_developer_exception
+    hresult_code: INTEGER
+            -- Status code.
+        require
+            applicable: is_developer_exception
 
-	hresult_facility: INTEGER
-       			-- Facility code.
-   		require
-       			applicable: is_developer_exception
+    hresult_facility: INTEGER
+            -- Facility code.
+        require
+            applicable: is_developer_exception
 
-	hresult_message: STRING
-       			-- Error message.
-   		require
-       			applicable: is_developer_exception
-		</code>
+    hresult_message: STRING
+            -- Error message.
+        require
+            applicable: is_developer_exception
+</code>
 
 Every call to COM should be wrapped into a <code> rescue </code> clause as follows: 
 <code>
-	some_feature is
-   		local
-      			retried: BOOLEAN
-      			...
-   		do
-        		if not retried then
-            			-- Call to COM.
-        		end
-   		rescue
-        		if is_developer_exception then
-            			-- Compare `hresult' to some predefined value
-            			-- and handle various cases,
-            			-- or display a dialog box with an error message
-            			-- `hresult_message'.
-        		end
-		        retried := True
-		        retry
-		end
-		</code>
+    some_feature
+        local
+            retried: BOOLEAN
+                ...
+        do
+            if not retried then
+                    -- Call to COM.
+            end
+        rescue
+            if is_developer_exception then
+                    -- Compare `hresult' to some predefined value
+                    -- and handle various cases,
+                    -- or display a dialog box with an error message
+                    -- `hresult_message'.
+            end
+            retried := True
+            retry
+        end
+</code>
 
 ==ECOM_STRUCTURE==
 
@@ -73,9 +73,9 @@ ECOM_VARIANT is a wrapper of the VARIANT structure. VARIANT is the Visual Basic
 
 This wrapper exposes the feature 
 <code>
-	variable_type: INTEGER
-        	-- Variable type. See class ECOM_VAR_TYPE for possible values. 
-		</code>
+    variable_type: INTEGER
+            -- Variable type. See class ECOM_VAR_TYPE for possible values. 
+</code>
 
 which specifies the actual type of the variant. The class has multiple features for typed access and setting of variables. 
 
@@ -83,9 +83,9 @@ which specifies the actual type of the variant. The class has multiple features
 
 <eiffel>ECOM_VARIANT_ACCESS</eiffel> provides the feature: 
 <code>
-	missing: ECOM_VARIANT
-		-- Value representing the default value of a COM optional argument.
-		-- Equivalent to an omitted VB argument, or C++ vtMissing, or .NET System.Reflection.Missing.
+    missing: ECOM_VARIANT
+            -- Value representing the default value of a COM optional argument.
+            -- Equivalent to an omitted VB argument, or C++ vtMissing, or .NET System.Reflection.Missing.
 </code>
 
 Many COM Automation servers have routines that take arguments with default values. This is very common, for example, in Microsoft Office applications such as Excel and Word. In Visual Basic, such arguments are optional and, when omitted, the server uses the default value. In languages that cannot omit arguments, a special VARIANT value representing the omitted argument must be passed. EiffelCOM applications can pass missing for this purpose. 
@@ -93,21 +93,22 @@ Many COM Automation servers have routines that take arguments with default value
 For example, the following adds a new workbook to Excel. The default argument tells Excel to decide for itself how many worksheets to put in the new workbook: 
 <code>
 class
-	MY_EXCEL_APPLICATION
+    MY_EXCEL_APPLICATION
 
 inherit
-	APPLICATION_PROXY
+    APPLICATION_PROXY
 
-	ECOM_VARIANT_ACCESS
+
+    ECOM_VARIANT_ACCESS
 
 feature
 
-	add_workbook is
-		local
-			workbook: WORKBOOK_PROXY
-		do
-			workbook := workbooks.add (missing, 0)
-		end
+    add_workbook
+        local
+            workbook: WORKBOOK_PROXY
+        do
+            workbook := workbooks.add (missing, 0)
+        end
 </code>