Obsolete.Fody

Helps keep usages of ObsoleteAttribute consistent.

See Milestones for release notes.

This is an add-in for Fody

It is expected that all developers using Fody become a Patron on OpenCollective. See Licensing/Patron FAQ for more information.

Usage

See also Fody usage.

NuGet installation

Install the Obsolete.Fody NuGet package and update the Fody NuGet package:

PM> Install-Package Fody
PM> Install-Package Obsolete.Fody

The Install-Package Fody is required since NuGet always defaults to the oldest, and most buggy, version of any dependency.

Add to FodyWeavers.xml

Add <Obsolete/> to FodyWeavers.xml

<Weavers>
  <Obsolete/>
</Weavers>

Your Code

[ObsoleteEx(
    Message = "Custom message.", 
    TreatAsErrorFromVersion = "2.0", 
    RemoveInVersion = "4.0", 
    ReplacementTypeOrMember = "NewClass")]
public class ClassToMark {}

Treat As Warning Mode

When the target assembly version is less than RemoveInVersion an ObsoleteAttribute with "treat as warning" will be injected. It will have the following format

[Obsolete("MESSAGE. Use 'REPLACED_WITH' instead. Will be treated as an error from version MARK_AS_VERSION_IN. Will be removed in version WILL_BE_REMOVED_IN_VERSION.")]

So given the above example when the assembly version is 1.0 the following will be injected

[Obsolete("Custom Message. Use 'NewClass' instead. Will be treated as an error from version 2.0.0. Will be removed in version 4.0.0.")]
    public class ClassToMark{}

Treat As Error Mode

When the target assembly version is greater than RemoveInVersion but less than TreatAsErrorFromVersion an ObsoleteAttribute with "treat as error" will be injected. It will have the following format

[Obsolete("MESSAGE. Use 'REPLACED_WITH' instead. Will be removed in version WILL_BE_REMOVED_IN_VERSION.", true)]

So given the above example when the assembly version is 3.0 the following will be injected

[Obsolete("Custom Message. Use 'NewClass' instead. Will be removed in version 4.0.0.", true)]
[EditorBrowsable(EditorBrowsableState.Advanced)]
public class ClassToMark{}

Build Error Mode

When the target assembly version is greater than TreatAsErrorFromVersion a build error will be generated. It will have the following format

Cannot process 'MEMBER_NAME'. The assembly version ASSEMBLY_VERSION is higher than version specified in 'RemoveInVersion' WILL_BE_REMOVED_IN_VERSION. The member should be removed or 'RemoveInVersion' increased.

So given the above example when the assembly version is 5.0 a compile error will be thrown with the following text

Cannot process 'ClassToMark'. The assembly version 5.0.0 is higher than version specified in RemoveInVersion 4.0.0. The member should be removed or RemoveInVersion increased.

Version convention

By default the prefix of AssemblyInformationalVersionAttribute will be used, if it can be parsed to a version. Otherwise the assembly version is used.

The Message property

The message property should only be used for useful information. The fact that it is obsoleted does not need to be reiterated in the message.

DO NOT use any of the following redundant messages

• "Do not call this method"
• "This method will be removed"
• "This method is obsolete"
• "The replacement method is"

Configuration Options

All configuration options are access by modifying the Obsolete node in FodyWeavers.xml

HideObsoleteMembers

When this is advanced or true obsolete members will also have [EditorBrowsable(EditorBrowsableState.Advanced)] added to them.

Defaults to advanced

When this is never obsolete members will also have [EditorBrowsable(EditorBrowsableState.Never)] added to them.

When this is off or false obsolete members will not have [EditorBrowsable] added to them.

<Obsolete HideObsoleteMembers='false'/>

TreatAsErrorFormat

The string used when informing the user what version the member will be treated as an error.

Defaults to Will be treated as an error from version {0}.

<Obsolete TreatAsErrorFormat="Will be treated as an error from version {0}. "/>

ThrowsNotImplementedText

The string used when informing the user when the member currently throws a NotImplementedException.

Defaults to The member currently throws a NotImplementedException.

<Obsolete ThrowsNotImplementedText="The member currently throws a NotImplementedException. "/>

RemoveInVersionFormat

The string used when informing the user what version the member will be removed it.

Defaults to Will be removed in version {0}.

<Obsolete RemoveInVersionFormat="Will be removed in version {0}. "/>

ReplacementFormat

The string used when informing the user of an alternative member to use instead of the obsolete member.

Defaults to Use {0} instead.

<Obsolete ReplacementFormat="Use {0} instead. "/>

StepType

Used in two cases

• To derive TreatAsErrorFromVersion if RemoveInVersion is not defined.
• To derive RemoveInVersion if TreatAsErrorFromVersion is not defined.

Defaults to Major. Other options are Minor and Patch

<Obsolete StepType="Minor"/>

Mute warnings about Obsolete usage

For ObsoleteAttribute is used and should not be replaced, use DoNotWarnAboutObsoleteUsageAttribute to mute Fody warnings during build time.

[Obsolete]
[DoNotWarnAboutObsoleteUsage]
public class LegacyCode {}

Icon

Icon courtesy of The Noun Project