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Configuration options for druntime.
The default way to configure the runtime is by passing command line arguments starting with --DRT- and followed by the option name, e.g. --DRT-gcopt to configure the GC. When command line parsing is enabled, command line options starting with --DRT- are filtered out before calling main, so the program will not see them. They are still available via rt_args().
Configuration via the command line can be disabled by declaring a variable for the linker to pick up before using it's default from the runtime:
extern(C) __gshared bool rt_cmdline_enabled = false;
Likewise, declare a boolean rt_envvars_enabled to enable configuration via the environment variable DRT_ followed by the option name, e.g. DRT_GCOPT:
extern(C) __gshared bool rt_envvars_enabled = true;
Setting default configuration properties in the executable can be done by specifying an array of options named rt_options:
extern(C) __gshared string[] rt_options = [ "gcopt=precise:1 profile:1"];
Evaluation order of options is rt_options, then environment variables, then command line arguments, i.e. if command line arguments are not disabled, they can override options specified through the environment or embedded in the executable.
Distributed under the Boost Software License 1.0. (See accompanying file LICENSE)
Rainer Schuetze
nothrow @nogc string rt_configOption(string opt, scope rt_configCallBack dg = null, bool reverse = false);
get a druntime config option using standard configuration options opt name of the option to retrieve dg if non-null, passes the option through this delegate and only returns its return value if non-null reverse reverse the default processing order cmdline/envvar/rt_options to allow overwriting settings in the delegate with values from higher priority
returns the options' value if
  • set on the command line as "--DRT-=value" (rt_cmdline_enabled enabled)
  • the environment variable "DRT_" is set (rt_envvars_enabled enabled)
  • rt_options[] contains an entry "=value"
  • null otherwise