ReswPlus - Advanced Code Generator for .resw Files

Now available as a Source Generator!

ReswPlus is a C# Source Generator for Visual Studio that enhances .resw files with a powerful set of features:

• Strongly typed static properties for safer and more efficient string access.
• Automatic generation of string formatting methods, supporting:
  • Typed and named parameters, literal strings, string references, and macros.
• Pluralization support for 196 languages, including handling empty states when the item count is zero.
• Variant support for managing multiple versions of a string.
• Generation of a markup extension for accessing strings with compile-time verification. (Deprecated — see Native AOT.)

✅ Feature Comparison

Feature	Resw	Resw + ReswPlus	Resx	Android XML (for reference)
Modify UI properties via resource files (x:uid)	✅	✅
Generate strongly typed accessors		✅	✅	✅
Generate string formatting methods		✅
Support pluralization		✅		✅
Support empty states		✅
Auto-generate string formatting methods		✅
Support literal strings in formatters		✅
Support macros in formatters		✅
Support string references in formatters		✅
Strongly typed string formatting		✅
Support resources in libraries		✅	✅
Support string variants (e.g., gender-based)		✅

📦 Getting Started

⚡ How to Install ReswPlus – Step-by-step installation guide.

ReswPlus recognizes a UWP project by the Windows.Foundation.UniversalApiContract reference it carries, and a Windows App SDK project by its own. A UWP project built for Native AOT has no such reference, so it declares what it is with the standard UseUwp property instead, which ReswPlus reads and trusts over the references:

<PropertyGroup>
    <UseUwp>true</UseUwp>
</PropertyGroup>

Without it, such a project is reported as RESWP0005 and no code is generated for it. The samples/UWP folder has one sample of each kind: ReswPlusUWPSample built with .NET Native, and ReswPlusNativeAotUwpSample built on modern .NET with Native AOT.

Injectable resource interfaces

🗨 How to inject generated resources

Pseudo-localization

🗨 How to test localization before translations are available

Translation checks

🗨 How to detect incomplete or drifting translations

Generator performance diagnostics

To include compiler-measured source-generator timings in detailed build output, enable:

<PropertyGroup>
    <ReswPlusReportGeneratorPerformance>true</ReswPlusReportGeneratorPerformance>
</PropertyGroup>

Then build with detailed verbosity:

dotnet build --verbosity detailed

The timing comes from the compiler rather than instrumentation inside generated code. The compiler-wide report also includes every other analyzer and source generator in the project. Roslyn does not expose incremental cache hits to a running generator, so ReswPlus tracks its named pipeline stages in its incrementality test suite instead; those tests verify that unchanged files are cached and that editing one resource regenerates only that resource.

⚡ Native AOT

Everything ReswPlus generates works when the app is compiled with Native AOT, except the markup extension, which is deprecated for that reason:

<!-- Works with Native AOT: resolved while the app is compiled -->
<TextBlock Text="{x:Bind strings:Resources.WelcomeTitle}" />

<!-- Deprecated, and does NOT work with Native AOT: created by the XAML parser while the page is read -->
<TextBlock Text="{strings:Resources Key=WelcomeTitle}" />

A page that uses the markup extension fails to load, with Markup extension could not provide value. It is still generated, so an app that does not use Native AOT keeps building, but it is marked [Obsolete]: a page that uses it reports WMC1500 on the line of the markup itself, so a build with TreatWarningsAsErrors will fail until it is rewritten or the warning suppressed.

x:Bind replaces it in almost every case. It reads the same generated members, takes a converter and a converter parameter the same way, and is checked while the app is compiled rather than when the page is shown:

Instead of	Write
{strings:Resources Key=Foo}	{x:Bind strings:Resources.Foo}
{strings:Resources Key=Foo, Converter={StaticResource C}}	{x:Bind strings:Resources.Foo, Converter={StaticResource C}}

x:Bind is not available everywhere the markup extension was: a Setter in a Style, and a standalone ResourceDictionary with no code-behind — a shared Styles.xaml, say — both lack the compiled-binding host x:Bind needs. Set those from code-behind using the same generated members.

This is not something a trimming directive can keep: preserving the generated types with rd.xml or a trimmer root does not change it.

🔧 Features

Strongly Typed Class Generator

ReswPlus generates a class that exposes all strings from your .resw files as strongly typed static properties, ensuring compile-time safety in both XAML and C#.

🗨 How to Generate a Strongly Typed Class

Pluralization Support

Easily add pluralization support for 196 languages, including correct handling of empty states when the count is zero.

🗨 How to Add Pluralization
⚙️ Handling Empty States
⚙️ Supported Languages

The plural rules follow the cardinal rules of Unicode CLDR 48, and are checked against the rules CLDR publishes by the test suite, so that a language whose rules CLDR revises is reported rather than silently declined with the rules of an older release. Ordinal rules (1st, 2nd, 3rd) and plural ranges (1–2) are not supported.

By default the plural rules are picked with the .NET UI culture, which comes from the display languages of the user. Windows resolves the resources themselves with the app runtime language list instead, so the two can disagree and a resource can be shown in one language while its plural form is picked with the rules of another. Set the following property to pick the plural rules with the same language the resources are resolved in:

<PropertyGroup>
    <ReswPlusUseApplicationLanguages>true</ReswPlusUseApplicationLanguages>
</PropertyGroup>

This is opt-in so that existing apps keep the behavior they were built against. Apps that let users pick a language in-app, through ApplicationLanguages.PrimaryLanguageOverride, should turn it on. A WinAppSDK project reads the override directly, so it also works when the app runs unpackaged, and needs Windows App SDK 1.6 or later.

String Formatting

ReswPlus simplifies ViewModels and Views by handling string formatting directly and generating strongly typed methods.

🗨 How to Use String Formatting
⚙️ Named Parameters
⚙️ Using String References
⚙️ Using Literal Strings
⚙️ Using Macros

String Variants

ReswPlus allows multiple variants of a string based on different criteria, such as gender-based messages or other conditions.

🗨 How to Use Variants

Resource Diagnostics

ReswPlus checks the content of your .resw files while it generates the code, and reports the inconsistencies that would otherwise only show up at runtime, in a language your team may not read.

Rule	Description
RESWP0006	A translated value drops placeholders its value in the default language uses, silently losing information.
RESWP0007	A value uses a placeholder that has no matching parameter in its #Format tag.
RESWP0008	A pluralized resource is missing the plural forms its language requires, which silently produces grammatically wrong text.
RESWP0009	Two resources of the same file conflict with each other, because their names only differ by case or because a plain resource collides with a pluralized one.
RESWP0010	A value that is used as a composite format string is malformed.
RESWP0012	A resource carries the name of a member the generated class declares itself, so it is skipped.
RESWP0013	A #Format tag declares the same parameter name twice, so the generated method renames all but the first.
RESWP0014	A .resw file could not be turned into code, and the rest of the project was generated without it.
RESWP0016	A resource exists in the default language but is missing from a translation.
RESWP0017	A translated resource does not exist in the default language.
RESWP0018	A translated value is identical to its default-language value.
RESWP0019	A translation has an incompatible plain, plural, or variant shape.
RESWP0020	A translation defines variants that do not exist in the default language.

Translation completeness is configurable with ReswPlusTranslationChecks=Off|Default|Strict. In the default mode, normal translation lag is informational and only defects that can break localized output are warnings. See Translation checks for the severity table and CI configuration.

Individual diagnostics can also be configured from .editorconfig:

dotnet_diagnostic.RESWP0006.severity = error

Tools

In addition to features to enrich resw files, ReswPlus also provides some interesting tools to improve your productivity or make it easier to use/support resw files in your workflow and localization process.

Convert from/to Android XML files

Unfortunately, not all localization tools and companies support .resw files. This becomes even more problematic when dealing with pluralization, as .resw does not support it by default.

To address this, ReswPlus includes a converter for seamless conversion between .resw and Android XML, a format that supports string pluralization and is widely compatible with existing localization tools.

Simply right click on the resw associated to the default language of your app and select ReswPlus > Export to Android XML format. To convert the Android files once localized, you can use the command-line tool provided with the nuget package (packages/ReswPlusLib.xxxx/Tools/ReswPlusCmd\ReswPlusCmd.exe with the following arguments xml-to-resw -i <folder path> <output path>.

If you don't want to use Visual Studio to convert your resw files to Android XML files, you can use the same command-line tool with the following arguments resw-to-xml -i <resw file path> <output file path>

Other programming languages

The current Source Generator supports only C#. If your project uses VB.NET, C++/CX, or C++/WinRT, you can use our legacy Visual Studio extension, available here