added support for specifying real kind via preprocessor flag

README.md

@@ -14,7 +14,49 @@ Currently, this module can be used to generate simple plots from Fortran.  Event
 The way it works is simply to generate a Python script with the plotting code, which
 is then executed from the command line using the Fortran ```execute_command_line``` function.
 
-The module requires a modern Fortran compiler (it uses various Fortran 2003/2008 features such as deferred-length strings). It should work fine with the latest gfortran or ifort compilers.  A simple script ```build.sh``` is provided for building the library and test program (requires gfortran and [FoBiS](https://github.com/szaghi/FoBiS)).  It will also build the HTML documentation if [FORD](https://github.com/Fortran-FOSS-Programmers/ford) is installed. A `fpm.toml` file is also provided for use with the [Fortran Package Manager](https://github.com/fortran-lang/fpm).
+### Compiling
+
+The module requires a modern Fortran compiler (it uses various Fortran 2003/2008 features such as deferred-length strings). It should work fine with the latest gfortran or ifort compilers.  
+
+A `fmp.toml` file is provided for compiling pyplot-fortran with the [Fortran Package Manager](https://github.com/fortran-lang/fpm). For example, to build:
+
+```
+fpm build --profile release
+```
+
+By default, the library is built with double precision (`real64`) real values. Explicitly specifying the real kind can be done using the following processor flags:
+
+Preprocessor flag | Kind  | Number of bytes
+----------------- | ----- | ---------------
+`REAL32`  | `real(kind=real32)`  | 4
+`REAL64`  | `real(kind=real64)`  | 8
+`REAL128` | `real(kind=real128)` | 16
+
+For example, to build a single precision version of the library, use:
+
+```
+fpm build --profile release --flag "-DREAL32"
+```
+
+To run the unit tests:
+
+```
+fpm test
+```
+
+To use `pyplot-fortran` within your fpm project, add the following to your `fpm.toml` file:
+```toml
+[dependencies]
+pyplot-fortran = { git="https://github.com/jacobwilliams/pyplot-fortran.git" }
+```
+
+or, to use a specific version:
+```toml
+[dependencies]
+pyplot-fortran = { git="https://github.com/jacobwilliams/pyplot-fortran.git", tag = "3.1.0" }
+```
+
+To generate the documentation using [ford](https://github.com/Fortran-FOSS-Programmers/ford), run: ```ford pyplot-fortran.md```
 
 ### Supported plot types
 
@@ -30,7 +72,7 @@ The module requires a modern Fortran compiler (it uses various Fortran 2003/2008
 
 The following example generates a plot of the sine function:
 
-```Fortran
+```fortran
  program test
 
  use,intrinsic :: iso_fortran_env, only: wp => real64
@@ -57,7 +99,7 @@ The following example generates a plot of the sine function:
 
 ### Documentation
 
- * The API documentation for the current ```master``` branch can be found [here](https://jacobwilliams.github.io/pyplot-fortran/).  This is generated by processing the source files with [FORD](https://github.com/Fortran-FOSS-Programmers/ford).  Note that the build script will also generate these files automatically in the ```doc``` folder, assuming you have FORD installed.
+ * The API documentation for the current ```master``` branch can be found [here](https://jacobwilliams.github.io/pyplot-fortran/).  This is generated by processing the source files with [FORD](https://github.com/Fortran-FOSS-Programmers/ford).  
 
 ### See also
 

src/pyplot_module.f90 → src/pyplot_module.F90

@@ -8,16 +8,39 @@
 !
 !# See also
 !   * Inspired by: [EasyPlot](https://pypi.python.org/pypi/EasyPlot)
+!
+!@note The default real kind (`wp`) can be
+!      changed using optional preprocessor flags.
+!      This library was built with real kind:
+#ifdef REAL32
+!      `real(kind=real32)` [4 bytes]
+#elif REAL64
+!      `real(kind=real64)` [8 bytes]
+#elif REAL128
+!      `real(kind=real128)` [16 bytes]
+#else
+!      `real(kind=real64)` [8 bytes]
+#endif
 
     module pyplot_module
 
-    use, intrinsic :: iso_fortran_env, only : real64, error_unit
+    use, intrinsic :: iso_fortran_env 
 
     implicit none
 
     private
 
-    integer, parameter, private :: wp = real64 !! Default real kind [8 bytes].
+#ifdef REAL32
+    integer,parameter,public :: pyplot_wp = real32   !! real kind used by this module [4 bytes]
+#elif REAL64
+    integer,parameter,public :: pyplot_wp = real64   !! real kind used by this module [8 bytes]
+#elif REAL128
+    integer,parameter,public :: pyplot_wp = real128  !! real kind used by this module [16 bytes]
+#else
+    integer,parameter,public :: pyplot_wp = real64   !! real kind used by this module [8 bytes]
+#endif
+
+    integer,parameter :: wp = pyplot_wp  !! local copy of `pyplot_wp` with a shorter name
 
     character(len=*), parameter :: tmp_file = 'pyplot_module_temp_1234567890.py' !! Default name of the temporary file
                                                                                  !! (this can also be user-specified).

tests/test.f90

@@ -7,8 +7,7 @@
 
     program test
 
-    use, intrinsic :: iso_fortran_env, only : wp => real64
-    use pyplot_module, only : pyplot
+    use pyplot_module, only : pyplot, wp => pyplot_wp
 
     implicit none