API / Apache Velocity Interview questions
Explain the internal working of Velocimacro resolution and invocation?
Calling a macro like #greet("Alex" true) triggers a distinct lookup and binding sequence separate from ordinary directive handling.
flowchart TD
A[Parser encounters #greet(...) call] --> B[VelocimacroManager looks up 'greet']
B --> C{Local macro defined in this template?}
C -- Yes --> D[Use local macro definition]
C -- No --> E{Found in a registered macro library?}
E -- Yes --> F[Use library macro definition]
E -- No --> G[Parse error: undefined macro]
D --> H[Bind call-site arguments to macro's declared parameters]
F --> H
H --> I[Render macro's body AST using those bound values]
I --> J[Output spliced into the calling template]
Argument binding is positional and happens by reference substitution: each parameter name inside the macro body is treated as a stand-in for whatever expression was passed at the call site, evaluated fresh on every invocation rather than passed by value once. This is why passing a reference (like $currentUser) into a macro reflects that reference's live value at each point the parameter is used inside the macro body, rather than freezing it at call time.
In what order does the VelocimacroManager typically resolve a macro call?
How are macro parameters bound to call-site arguments?
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