ft: 添加port_env的说明和示例

README.md

@@ -17,77 +17,78 @@ default_env
 
 After that eNpc should read your old rebar.config `port_specs` and `port_env` settings as expected (it is rebar2's port compiler after all...).
 
-%% Supported configuration variables:
-%%
-%% * port_specs - Erlang list of tuples of the forms
-%%                {ArchRegex, TargetFile, Sources, Options}
-%%                {ArchRegex, TargetFile, Sources}
-%%                {TargetFile, Sources}
-%%
-%%                Note that if you want to use any of the rebar3 variables
-%%                below you must MUST use a ${}-style to get the expansion
-%%                to work. e.g. to expand REBAR_DEPS_DIR, do something like:
-%%
-%%                {port_specs, [{"priv/nif.so",
-%%                               ["c_src/nif.c",
-%%                                "${REBAR_DEPS_DIR}/foo/bar.c"]}]}.
-%%
-%%                This is a _very_ good way to be able to use your code both
-%%                as a top level app and a dependency.
-%%
-%%                CAVEAT! Not using {} is broken for the moment.
-%%
-%% * port_env - Erlang list of key/value pairs which will control
-%%              the environment when running the compiler and linker.
-%%              Variables set in the surrounding system shell are taken
-%%              into consideration when expanding port_env. Note that
-%%              for ERL_LDFLAGS, -lerl_interface is used for only those
-%%              Erlang/OTP versions where it exists (those prior to
-%%              version 23.0).
-%%
-%%              By default, the following variables are defined:
-%%              CC       - C compiler
-%%              CXX      - C++ compiler
-%%              CFLAGS   - C compiler
-%%              CXXFLAGS - C++ compiler
-%%              LDFLAGS  - Link flags
-%%              ERL_CFLAGS  - default -I paths for erts and ei
-%%              ERL_LDFLAGS - default -L and -lerl_interface -lei
-%%              DRV_CFLAGS  - flags that will be used for compiling
-%%              DRV_LDFLAGS - flags that will be used for linking
-%%              EXE_CFLAGS  - flags that will be used for compiling
-%%              EXE_LDFLAGS - flags that will be used for linking
-%%              ERL_EI_LIBDIR - ei library directory
-%%              DRV_CXX_TEMPLATE      - C++ command template
-%%              DRV_CC_TEMPLATE       - C command template
-%%              DRV_LINK_TEMPLATE     - C Linker command template
-%%              DRV_LINK_CXX_TEMPLATE - C++ Linker command template
-%%              EXE_CXX_TEMPLATE      - C++ command template
-%%              EXE_CC_TEMPLATE       - C command template
-%%              EXE_LINK_TEMPLATE     - C Linker command template
-%%              EXE_LINK_CXX_TEMPLATE - C++ Linker command template
-%%
-%%              Note that if you wish to extend (vs. replace) these variables,
-%%              you MUST include a shell-style reference in your definition.
-%%              e.g. to extend CFLAGS, do something like:
-%%
-%%              {port_env, [{"CFLAGS", "$CFLAGS -MyOtherOptions"}]}
-%%
-%%              It is also possible to specify platform specific options
-%%              by specifying a triplet where the first string is a regex
-%%              that is checked against Erlang's system architecture string.
-%%              e.g. to specify a CFLAG that only applies to x86_64 on linux
-%%              do:
-%%
-%%              {port_env, [{"x86_64.*-linux", "CFLAGS",
-%%                           "$CFLAGS -X86Options"}]}
-%%
-%%              Cross-arch environment variables to configure toolchain:
-%%              GET_ARCH to set the tool chain name to use
-%%              GET_ARCH_WORDSIZE (optional - to determine word size)"
-%%              word size is 32
-%%              GET_ARCH_VSN (optional - "
-%%              l version of CC/CXX is requested),
+###
+```
+ Supported configuration variables:
+ * port_specs - Erlang list of tuples of the forms
+                {ArchRegex, TargetFile, Sources, Options}
+                {ArchRegex, TargetFile, Sources}
+                {TargetFile, Sources}
+
+                Note that if you want to use any of the rebar3 variables
+                below you must MUST use a ${}-style to get the expansion
+                to work. e.g. to expand REBAR_DEPS_DIR, do something like:
+
+                {port_specs, [{"priv/nif.so",
+                               ["c_src/nif.c",
+                                "${REBAR_DEPS_DIR}/foo/bar.c"]}]}.
+
+                This is a _very_ good way to be able to use your code both
+                as a top level app and a dependency.
+
+                CAVEAT! Not using {} is broken for the moment.
+
+ * port_env - Erlang list of key/value pairs which will control
+              the environment when running the compiler and linker.
+              Variables set in the surrounding system shell are taken
+              into consideration when expanding port_env. Note that
+              for ERL_LDFLAGS, -lerl_interface is used for only those
+              Erlang/OTP versions where it exists (those prior to
+              version 23.0).
+
+              By default, the following variables are defined:
+              CC       - C compiler
+              CXX      - C++ compiler
+              CFLAGS   - C compiler
+              CXXFLAGS - C++ compiler
+              LDFLAGS  - Link flags
+              ERL_CFLAGS  - default -I paths for erts and ei
+              ERL_LDFLAGS - default -L and -lerl_interface -lei
+              DRV_CFLAGS  - flags that will be used for compiling
+              DRV_LDFLAGS - flags that will be used for linking
+              EXE_CFLAGS  - flags that will be used for compiling
+              EXE_LDFLAGS - flags that will be used for linking
+              ERL_EI_LIBDIR - ei library directory
+              DRV_CXX_TEMPLATE      - C++ command template
+              DRV_CC_TEMPLATE       - C command template
+              DRV_LINK_TEMPLATE     - C Linker command template
+              DRV_LINK_CXX_TEMPLATE - C++ Linker command template
+              EXE_CXX_TEMPLATE      - C++ command template
+              EXE_CC_TEMPLATE       - C command template
+              EXE_LINK_TEMPLATE     - C Linker command template
+              EXE_LINK_CXX_TEMPLATE - C++ Linker command template
+
+              Note that if you wish to extend (vs. replace) these variables,
+              you MUST include a shell-style reference in your definition.
+              e.g. to extend CFLAGS, do something like:
+
+              {port_env, [{"CFLAGS", "$CFLAGS -MyOtherOptions"}]}
+
+              It is also possible to specify platform specific options
+              by specifying a triplet where the first string is a regex
+              that is checked against Erlang's system architecture string.
+              e.g. to specify a CFLAG that only applies to x86_64 on linux
+              do:
+
+              {port_env, [{"x86_64.*-linux", "CFLAGS",
+                           "$CFLAGS -X86Options"}]}
+
+              Cross-arch environment variables to configure toolchain:
+              GET_ARCH to set the tool chain name to use
+              GET_ARCH_WORDSIZE (optional - to determine word size)"
+              word size is 32
+              GET_ARCH_VSN (optional - "
+              l version of CC/CXX is requested),
 
 
 {port_specs, [
@@ -119,4 +120,5 @@ After that eNpc should read your old rebar.config `port_specs` and `port_env` se
     {"darwin10.*-32$", "LDFLAGS", "-arch i386"},
 
     {"win32", "CXXFLAGS", "$CXXFLAGS /O2 /DNDEBUG"}
-]}.
+]}.
+```