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It is also possible to retrieve a stack traceback from anywhere in a program. For this you need to use the GNAT.Traceback API. This package includes a procedure called Call_Chain that computes a complete stack traceback, as well as useful display procedures described below. It is not necessary to use the -E gnatbind option in this case, because the stack traceback mechanism is invoked explicitly.

In the following example we compute a traceback at a specific location in the program, and we display it using GNAT.Debug_Utilities.Image to convert addresses to strings:


with Ada.Text_IO; with GNAT.Traceback; with GNAT.Debug_Utilities; procedure STB is use Ada; use GNAT; use GNAT.Traceback; procedure P1 is TB : Tracebacks_Array (1 .. 10); -- We are asking for a maximum of 10 stack frames. Len : Natural; -- Len will receive the actual number of stack frames returned. begin Call_Chain (TB, Len); Text_IO.Put ("In STB.P1 : "); for K in 1 .. Len loop Text_IO.Put (Debug_Utilities.Image (TB (K))); Text_IO.Put (' '); end loop; Text_IO.New_Line; end P1; procedure P2 is begin P1; end P2; begin P2; end STB;

     $ gnatmake stb
     $ stb
     In STB.P1 : 16#0040_F1E4# 16#0040_14F2# 16#0040_170B# 16#0040_171C#
     16#0040_1461# 16#0040_11C4# 16#0040_11F1# 16#77E8_92A4#