ThinBasic.NET

.NET wrapper for the ThinBasic scripting engine (thinCore.dll).
Embed ThinBasic scripts in .NET apps, inject host constants/keywords, and parse callback arguments.

Requirements

Item	Detail
OS	Windows 10+
Architecture	x86 only (PlatformTarget=x86)
.NET	net8.0-windows / net9.0-windows / net10.0-windows
Native	Ships thinCore.dll + thinBasic_UI.dll (ThinBasic 1.14 era)

x64 / Arm64 processes cannot load the bundled 32-bit native DLLs.

NuGet

PM> Install-Package ThinBasic.NET

Consumer projects must target Windows x86 (or Prefer 32-bit) so thinCore.dll can load.

Important notes

Strings (ANSI BSTR)

thinCore string parameters/returns use ANSI BSTRs (SysAllocStringByteLen), not Unicode BStr / LPStr.
This package marshals them manually. Prefer ASCII / system-ANSI-safe text for symbol names and paths.

For ThinBasicStringCallback return values, allocate with:

return Thinbasic.AllocReturnString("hello");

Ownership of that BSTR is transferred to thinCore — do not free it yourself.

Callbacks and GC

LoadSymbol / LoadSymbolEx accept managed delegates and keep them rooted until:

Thinbasic.ClearSymbolCallbacks();

Call ClearSymbolCallbacks only when no script may still invoke those keywords.

Direct variable / array pointers

GetVariableNumberDirect / ChangeVariable*Direct need the return value of VariableGetInfoEx (variable structure pointer), not the DataPtr out-parameter.

Runtime errors

Script runtime errors may show a thinBasic error dialog and leave process-wide engine state dirty.
Prefer validating scripts; avoid relying on failed Run calls inside long-lived hosts.
GetLastError can remain sticky across Release / next Init in some failure paths.

Isolation

InitIsolated / InitCheckScript take an isolation directory for extracted modules/DLLs.
After InitIsolated, IsIsolated() is non-zero and IsolationPath() returns that path.
Isolation flags may remain set for the process after Release (thinCore global state).

Hash tables

HashNew / HashSet / HashGet / HashFree use thinCore’s internal string hash storage.
Init is not required. Keys are case-sensitive; always HashFree handles you create (including clones).

Quick start

using ThinBasic.NET.Core;

int h = Thinbasic.Init(0, 0, "thinbasic");
if (h != 0)
{
    Console.WriteLine("Init failed: " + Thinbasic.GetLastError());
    return;
}

Thinbasic.AddEquate("%HOST_EQ", string.Empty, 7, (int)Enums.EquateType.Number);

int hostCalls = 0;
Thinbasic.LoadSymbol("HostFlag", () => hostCalls++, Enums.ForceOverWrite);
Thinbasic.LoadSymbol("HostNum", () => 123.5, Enums.ForceOverWrite);
Thinbasic.LoadSymbol("HostStr$", () => Thinbasic.AllocReturnString("hello"), Enums.ForceOverWrite);

string script = File.ReadAllText(@"Sample\test.tbasic", Encoding.UTF8);
int result = Thinbasic.Run(
    h,
    script,
    (int)Enums.BufferType.IsScript,
    0, 0, 0, 0,
    (int)Enums.CallingProgram.Console,
    0);

int lastError = Thinbasic.GetLastError();
Thinbasic.Release(h);
Thinbasic.ClearSymbolCallbacks();

if (lastError != 0)
{
    Console.WriteLine("Script error: " + lastError);
}

Parser callbacks

Thinbasic.LoadSymbol("HostAdd", () =>
{
    if (Thinbasic.CheckOpenParensMandatory() == 0) return 0;
    Thinbasic.ParseNumber(out double a);
    if (Thinbasic.CheckCommaMandatory() == 0) return 0;
    Thinbasic.ParseNumber(out double b);
    if (Thinbasic.CheckCloseParensMandatory() == 0) return 0;
    return a + b;
}, Enums.ForceOverWrite);

Isolation

string iso = Path.Combine(Path.GetTempPath(), "my-iso");
Directory.CreateDirectory(iso);

int h = Thinbasic.InitIsolated(0, 0, "thinbasic", iso);
// Thinbasic.IsIsolated() != 0
// Thinbasic.IsolationPath() ~= iso

Thinbasic.Run(h, "DIM n AS LONG\r\nn = 1\r\n",
    (int)Enums.BufferType.IsScript, 0, 0, 0, 0,
    (int)Enums.CallingProgram.Console, 0);

Thinbasic.Release(h);

Examples project

dotnet run --project ThinBasic.Example -c Release -p:Platform=x86 -- embed
dotnet run --project ThinBasic.Example -c Release -p:Platform=x86 -- host
dotnet run --project ThinBasic.Example -c Release -p:Platform=x86 -- parser
dotnet run --project ThinBasic.Example -c Release -p:Platform=x86 -- array
dotnet run --project ThinBasic.Example -c Release -p:Platform=x86 -- isolated
dotnet run --project ThinBasic.Example -c Release -p:Platform=x86 -- hash

Build & test

Requires Visual Studio 2022/2026 (or .NET SDK 8+) on Windows.

dotnet build ThinBasic.NET\ThinBasic.NET.csproj -c Release -p:Platform=x86
dotnet test ThinBasic.NETTests\ThinBasic.NETTests.csproj -c Release -p:Platform=x86

API surface (summary)

Area	Highlights
Lifecycle	Init, InitIsolated, InitCheckScript, Run, Release, AddIncludePath
Host data	AddEquate, AddVariable, ChangeVariable*, VariableGet*, FunctionSimpleCall
Keywords	LoadSymbol / LoadSymbolEx (+ delegate overloads), AllocReturnString, ClearSymbolCallbacks
Parser	CheckOpen/CloseParens*, CheckComma*, ParseNumber / ParseString, PutBack, GetToken*
Arrays	VariableIsArray, ArrayGetElements / Ptr / Info, VariableRedim, *Direct
Isolation	IsIsolated, IsolationPath, IsBundled, ResourcesCount / GetFile / GetBuffer
Hash	HashNew / Free / Set / Add / Get / GetDefault / Exists / Del / Count / Clone / Clear / GetKeys / ToString / Cap* / Validate

License

Copyright (c) 2017-2026 Ji-Feng Tsai.
ThinBasic Copyright (c) Eros Olmi ThinBASIC Interpreter.
Code released under the MIT license.

TODO

• More thinCore.dll APIs (class)

Donation

If this application help you reduce time to coding, you can give me a cup of coffee :)

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