Examples of Quick-Fixes

Quick-fixes are available in a variety of circumstances, which is too large to be listed. ReSharper provides a total of more than 700 quick-fixes in all supported languages. Here we will show how to use them using a small selection of situations:

• Type mismatch
• Undefined variable
• Undefined method call
• Forgotten method return
• Missing using directives
• Missing async modifier
• Converting a loop to a LINQ expression
• Migrating to IEnumerable in method parameters and returns
• Converting assignment statements to object initializers
• Converting a static method invocation to extension method call
• Converting an anonymous method to lambda expression
• Converting to auto-property
• Making type parameter invariant

Type Mismatch

Whenever the type of an expression cannot be implicitly cast to the type applicable to the expression context, ReSharper detects this error and highlights it in the editor. After positioning the caret at the highlighted error and pressing Alt+Enter, the user can choose a quick-fix from the following list:

The effects of applying the proposed quick-fixes are illustrated in the table below.

Quick-fix	Effect
Cast to 'string'
Safely cast to 'string'
Change type of 'o' to 'string'
Change type of 's' to 'object'
Call ToString()

Undefined Variable

Whenever ReSharper detects an undefined variable in your code, the error is highlighted. After positioning the caret at the highlighted error and pressing Alt+Enter you will be presented with the following list of quick-fixes:

The effects of applying the proposed quick-fixes are illustrated in the table below.

Quick-fix	Effect
Create local variable 's'	A new local variable s is created proposing you to choose the desired type.
Create parameter 's' in the containing method	A new parameter is added to the method signature:
Create other	Opens a sub-menu where you can choose to create a field or a property in the corresponding class. For example, if you choose to create a field, a new private field s is created in the current class. The following suggestion appears helping the user to choose the correct type of the new field:
Change all 's'	If you choose Change all, the following suggestion displays: Type the new name only once; ReSharper changes all the other occurrences of the undefined variable:

Undefined Method Call

Whenever ReSharper detects a call to an undefined method in your code, the error gets highlighted. After positioning the caret at the highlighted error and pressing Alt+Enter, ReSharper displays the following list of quick-fixes:

After applying a quick-fix, the code gets modified as shown in the following table:

Quick-fix	Effect
Create method 'ResolveManagedReference'	This quick-fix declares a new method with the signature derived from the method call, benefiting developers who prefer top-down programming. In our example, ReSharper creates the following declaration, correctly guessing the return type: ReSharper also suggests applicable types and a name for the parameter of the new method:
Create other	This sub-menu includes other quick-fixes involving creation of auxiliary code. For example: Create parameter 'ResolveManagedReference' in containing method and update hierarchy This quick-fix creates a new parameter in the current method from the unresolved symbol, and introduces this parameter into any base members and inheritors that the method may have. or: Create parameter 'ResolveManagedReference' in containing method This quick-fix creates a new parameter in the current method from the unresolved symbol but doesn't update its base methods or inheritors.
Change all 'ResolveManagedReference'	Similarly to the corresponding quick-fix for undefined variables, this quick-fix allows the user to quickly replace all occurrences of the symbol someMethod.

Forgotten Method Return

If a method is expected to return a value but you forgot to provide a return statement, ReSharper warns you about that by highlighting the closing bracket of the troublesome method. After positioning the caret at the highlighted error and pressing Alt+Enter you will be presented with the following quick-fix:

Missing Using Directives

Whenever you have a type name in your code that cannot be resolved because you forgot to write a corresponding using directive in your file, a small pop-up window suggests you to import the type:

Press Alt+Enter, and the appropriate using directive will be inserted. Should there be multiple types with the matching name, you will be asked to choose the one you wish to use (see Importing Namespaces for details).

If for some reason you chose not to import a required namespace when the pop-up window was displayed, or if you cleared the Show the "Import namespace" action using popup check box on the Code Inspection | Settings page of ReSharper options, you can import a type at any time by putting the caret at the non-imported type, pressing Alt+Enter after a quick-fix shows up, and selecting the Import type [name] quick-fix:

Missing async modifier

If you have a method that contains the await operator, but that is not defined as asynchronous, ReSharper detects such mismatch and offers to fix this problem using the corresponding quick-fix.

Before:
Applying the quick-fix:
After:

Converting a loop to a LINQ expression

With C# 3.0 and LINQ, developers are able to write data-intensive code more easily by directly describing their intent to the compiler. ReSharper detects code that can be rewritten using LINQ syntax and offers to perform the conversion automatically:

Before:
Applying the quick-fix:
After:

Migrating to IEnumerable in method parameters and returns

ReSharper scans your code base to detect methods that can safely return and accept IEnumerable instead of a more specific type such as Array, List, or ArrayList:

Before:
Applying the quick-fix:
After:

Converting assignment statements to object initializers

ReSharper provides both a context action and a quick-fix to convert assignment statements into object initializers. The context action lets you add field assignments to an initializer one-by-one, whereas the quick-fix adds them all in one go. Here's how the quick-fix works:

Before:
Applying the quick-fix:
After:

Converting a static method invocation to extension method call

When you invoke an extension method as a traditional C# static method, ReSharper helps you quickly comply with standard extension method call practices:

Before:
Applying the quick-fix:
After:

Converting an anonymous method to lambda expression

ReSharper suggests converting anonymous methods to lambda expressions. The reverse functionality is provided as a context action.

Before:
Applying the quick-fix:
After:

Converting to auto-property

ReSharper makes it quick to convert traditional, private field-based properties to automatic properties implemented in C# 3.0. For more information, see Using Auto-Properties.

Before:
Applying the quick-fix:
After:

Making type parameter invariant

When a usage of a type parameter violates its variance, ReSharper suggests to make the parameter invariant:

Before:
Applying the quick-fix:
After: