netexpr-migration.md

netexpr modern expression API review

The migration uses MathParser, MathBinder, the standard symbol catalog and interpreted evaluation from LTRData.MathExpression 1.1.0. All existing targets remain: net35, net40, net8.0, net9.0 and net10.0.

Formula arguments are joined as before. Variables are prompted in first-use order, with case-insensitive name=value assignments and invariant numeric syntax. Repeated names share a slot; reassignment updates it while other values are pending. Blank input is ignored; EOF with missing values returns a useful error. Parse and binding errors include diagnostic codes and source spans.

The modern language has right-associative power (2^3^2 = 512), with power before unary sign (-2^2 = -4). ^ and ** both mean power. Shift/bitwise syntax and the old parser's accidental precedence rules are not retained. The authoritative language specification describes functions, constants and implicit multiplication.

Output and the historical numeric exit code are retained. The printed result is invariant; the exit code uses VB CInt rounding (ties to even), or -1 for errors, non-finite values or conversion overflow. A nonzero result is therefore not a conventional process-success code, and a shell may truncate it.

Build through the local feed

Set LocalNuGetPath to a shared package directory. In the Library experimental checkout, build these projects in Release, which produces their NuGet packages:

dotnet build LTRData.Extensions/LTRData.Extensions.csproj -c Release
dotnet build LTRData.MathExpression/LTRData.MathExpression.csproj -c Release

Configure this repository's local NuGet.Config to include the shared directory, then build and run the review executable:

dotnet restore netexpr/netexpr.vbproj --force-evaluate
dotnet build netexpr/netexpr.vbproj -c Release --no-restore
dotnet run --project netexpr.Review/netexpr.Review.csproj -c Release

The review executable calls the real command-line entry point with redirected streams under Swedish culture, checking 13 scenarios. It returns zero on success, independently of the calculator's numeric exit-code convention. The only ProjectReference is between projects in this repository; Library is consumed through packages. Directory.Build.props now has the standard filename casing so Unix builds apply the same common settings.

The focused netexpr package review workflow repeats the chain on Linux and Windows. It uses a pinned Library commit, a shared output feed, package source mapping and a fresh cache. Nothing is published to a NuGet server. For equivalent local configuration, see Library's local package workflow.

The application owner has built and tested this migration successfully. Saved formulas and shell scripts remain useful review cases, particularly any that use old operator syntax or assume a conventional zero-on-success exit code.