Build Info

When you run kp compile (or kp build) and your manifest includes a defines section, KnitPkg automatically generates a compile-time header at knitpkg/build/BuildInfo.mqh before invoking the MetaEditor compiler.

This header exports project metadata and user-defined constants as MQL preprocessor #define directives, making them available at compile time — no runtime parsing, no string manipulation.

Note

BuildInfo.mqh is auto-generated. Do not edit it manually; your changes will be overwritten on the next kp compile or kp build.

Defining constants

Constants are declared in the defines section of knitpkg.yaml. There are two subsections, and they can be used independently or together: from_manifest and extra.

'defines' in manifest

defines:
  from_manifest:
    MANIFEST_VERSION:     version       # value of version      → #define MANIFEST_VERSION "2.0.1"
    MANIFEST_ORG:         organization  # value of organization → #define MANIFEST_ORG "douglasrechia"
    MANIFEST_AUTHOR:      author        # value of author       → #define MANIFEST_AUTHOR "Douglas Rechia"
    MANIFEST_DESCRIPTION: description   # value of description  → #define MANIFEST_DESCRIPTION "KnitPkg for Metatrader - Expert Demo"
  extra:
    MQL_STORE_VERSION:    '2.1'         # string value          → #define MQL_STORE_VERSION "2.1"
    MAX_BARS:             500           # numeric value         → #define MAX_BARS 500
    FEATURE_X_ENABLED:    true          # true                  → #define FEATURE_X_ENABLED true
    FEATURE_Y_ENABLED:    null          # null                  → #define FEATURE_Y_ENABLED 

In the from_manifest section, the generated constant value is always the value of the field as it appears in knitpkg.yaml. In the extra, a flat key/value map for constants that do not come from the manifest are defined.

Adding constants at compile time

You can inject constants directly from the command line using --define or -D. This is useful for CI pipelines, release channels, and feature flags that should not be stored in the manifest:

kp compile -D NIGHTLY
kp compile -D BUILD_TYPE=release
kp compile -D FEATURE_X_ENABLED -D MAX_BARS=500

Why this matters

The BuildInfo.mqh feature is about controlling your Expert/Indicator at compile time, instead of scattering hardcoded values and #defines across your codebase.

Some typical use cases:

• Correct version and metadata in the EA properties
  Instead of duplicating version and description strings in multiple places, you define them once in the manifest and expose them via BuildInfo.mqh, then wire them directly into the EA "Common" tab using #property:

  #include "../knitpkg/build/BuildInfo.mqh"
  
  #property copyright   "Copyright © 2026 " + MANIFEST_AUTHOR + ". All rights reserved."
  #property link        "https://knitpkg.dev"
  #property version     (string)MQL_STORE_VERSION
  
  #property description ""
  #property description "Version: " + MANIFEST_VERSION
  #property description ""
  #property description "Description: " + MANIFEST_DESCRIPTION
  #property description "Organization: " + MANIFEST_ORG
  #property description "Author: " + MANIFEST_AUTHOR
  #property description ""
  #property description "Powered by KnitPkg for MetaTrader"
  #property description "https://knitpkg.dev"
  

• Feature flags
  Enable or disable blocks of code without touching source files:

  kp compile -D FEATURE_RISK_MODEL_V2
  

  #include "../knitpkg/build/BuildInfo.mqh"
  
  double CalculateRisk() 
    { 
      #ifdef FEATURE_RISK_MODEL_V2 
          return NewRiskModel(); 
      #else 
          return LegacyRiskModel(); 
      #endif 
    }
  

• Environment-specific builds
  Generate binaries for different brokers, environments or channels from the same source tree:

  kp compile -D BUILD_CHANNEL=beta 
  kp compile -D BUILD_CHANNEL=production
  

  #include "../knitpkg/build/BuildInfo.mqh"
  
  /// .....
  
  #ifdef BUILD_CHANNEL 
      Print("Build channel: ", BUILD_CHANNEL); 
  #endif
  

This way:

• The manifest is the single source of truth for your project metadata.
• BuildInfo.mqh turns that metadata (plus any -D flags) into compile-time constants.
• Your MQL code stays clean and declarative, focusing on logic instead of plumbing values around.

Together with kp compile --define / -D, this gives you a light but powerful build system for MQL: from a single codebase, you can produce multiple variants (debug, store, internal, nightly, broker-specific, etc.) just by changing compile-time constants — no branching, no manual edits.