trace_var(symbol, cmd ) â nil
trace_var(symbol) {|val| block } â nil
trace_var(symbol) {|val| block } â nil
Instance Public methods
Controls tracing of assignments to global variables. The parameter +symbol_
identifies the variable (as either a string name or a symbol identifier).
cmd (which may be a string or a Proc object) or block
is executed whenever the variable is assigned. The block or
Proc object receives the variable's new value as a
parameter. Also see Kernel::untrace_var.
1 2 3 | trace_var :$_, proc {|v| puts "$_ is now '#{v}'" }$_ = "hello"$_ = ' there' |
produces:
1 2 | $_ is now 'hello'$_ is now ' there' |
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