String.Format Diagnostic (Roslyn)

String Format Diagnostic enables the validation of format strings at compile-time.

Why Do This?

Why? This turns a set of run-time exceptions into compile-time warnings!

Supported Methods

.ToString() on

Int16, Int32, Int64, UInt16, UInt32, UInt64
Byte, UByte
Double, Single
Decimal
DateTime, TimeSpan, DateTimeOffset
Enum

.ParseExact on

DateTime
DateTimeOffset

.TryParseExact on

DateTime
DateTimeOffset

Note: The method overload which you can supply an array of format strings are not supported,

C#Visual Basic

Edit|Remove

System.Diagnostics.Debug.WriteLineSystem.Diagnostics.Trace.TraceErrorSystem.Diagnostics.Trace.TraceInformationSystem.Diagnostics.Trace.TraceWarningSystem.IO.TextWriter.WriteLineSystem.String.FormatSystem.Console,WriteSystem.Console.WritelineSystem.Text.StringBuilder.AppendFormatString.Format("{0}{2}", 0, 1);Console.Write("{0}{2}", 0, 1);Console.WriteLine("{0}{2}", 0, 1);

String.Format("{0}{2}", 0, 1)Console.Write("{0}{2}", 0, 1)Console.WriteLine("{0}{2}", 0, 1)

System.Diagnostics.Debug.WriteLine System.Diagnostics.Trace.TraceError System.Diagnostics.Trace.TraceInformation System.Diagnostics.Trace.TraceWarning System.IO.TextWriter.WriteLine System.String.Format System.Console,Write System.Console.Writeline System.Text.StringBuilder.AppendFormat  String.Format("{0}{2}", 0, 1); Console.Write("{0}{2}", 0, 1); Console.WriteLine("{0}{2}", 0, 1);

Example of Supported Validation Rules

Currently it supports the following validation checks

Is the argument index valid
Unexpected Characters
Unexpexted Reached End Of Text
Argument Index Value is less than the inbuilt limit of 1000000 (.net framework)
Alignment Width Value is less that the inbuild limit of 1000000 (.net framework)

Also gives information that the formatstring contains no argument index references. Eg {1}

Format Argument of an hole is now validated against the type of the refered to object.

The formatstring argument can be:-

A String Literal "Hello {0}"
A Const variable

Diagnostic available for both VB.net and C#.

VS2014 (ctp4)

Note: These are beta releases, so bug report are very welcome.

If you discover a format string thet is incorrect validated please file a bug report on the project site, as the validation rules applied are my intereptation of the available documentation.

AdamSpeight2008