adds tutorials and documentation for file readers and writers.

bonobo/_api.py

@@ -10,6 +10,7 @@ __all__ += ['Bag', 'Graph']
 
 # Filesystem. This is a shortcut from the excellent filesystem2 library, that we make available there for convenience.
 from fs import open_fs as _open_fs
+
 open_fs = lambda url, *args, **kwargs: _open_fs(str(url), *args, **kwargs)
 __all__ += ['open_fs']
 
@@ -38,7 +39,11 @@ def get_examples_path(*pathsegments):
     return str(pathlib.Path(os.path.dirname(__file__), 'examples', *pathsegments))
 
 
+def open_examples_fs(*pathsegments):
+    return open_fs(get_examples_path(*pathsegments))
+
 __all__.append(get_examples_path.__name__)
+__all__.append(open_examples_fs.__name__)
 
 
 def _is_interactive_console():

bonobo/examples/tutorials/_services.py

@@ -0,0 +1,5 @@
+from bonobo import open_examples_fs
+
+
+def get_services():
+    return {'fs': open_examples_fs('datasets')}

bonobo/examples/tutorials/tut02_01_read.py

@@ -1,15 +1,11 @@
 import bonobo
-from bonobo.commands.run import get_default_services
 
 graph = bonobo.Graph(
-    bonobo.FileReader(path='datasets/coffeeshops.txt'),
+    bonobo.FileReader(path='coffeeshops.txt'),
     print,
 )
 
-
-def get_services():
-    return {'fs': bonobo.open_fs(bonobo.get_examples_path())}
-
-
 if __name__ == '__main__':
-    bonobo.run(graph, services=get_default_services(__file__, get_services()))
+    bonobo.run(graph, services={
+        'fs': bonobo.open_examples_fs('datasets')
+    })

bonobo/examples/tutorials/tut02_02_write.py

@@ -0,0 +1,17 @@
+import bonobo
+
+
+def split_one(line):
+    return line.split(', ', 1)
+
+
+graph = bonobo.Graph(
+    bonobo.FileReader(path='coffeeshops.txt'),
+    split_one,
+    bonobo.JsonWriter(path='coffeeshops.json'),
+)
+
+if __name__ == '__main__':
+    bonobo.run(graph, services={
+        'fs': bonobo.open_examples_fs('datasets')
+    })

bonobo/examples/tutorials/tut02_03_writeasmap.py

@@ -0,0 +1,27 @@
+import bonobo, json
+
+
+def split_one_to_map(line):
+    k, v = line.split(', ', 1)
+    return {k: v}
+
+
+class MyJsonWriter(bonobo.JsonWriter):
+    prefix, suffix = '{', '}'
+
+    def write(self, fs, file, lineno, row):
+        return bonobo.FileWriter.write(
+            self, fs, file, lineno, json.dumps(row)[1:-1]
+        )
+
+
+graph = bonobo.Graph(
+    bonobo.FileReader(path='coffeeshops.txt'),
+    split_one_to_map,
+    MyJsonWriter(path='coffeeshops.json'),
+)
+
+if __name__ == '__main__':
+    bonobo.run(graph, services={
+        'fs': bonobo.open_examples_fs('datasets')
+    })

bonobo/io/json.py

@@ -10,6 +10,7 @@ __all__ = [
 
 class JsonHandler:
     eol = ',\n'
+    prefix, suffix = '[', ']'
 
 
 class JsonReader(JsonHandler, FileReader):
@@ -24,9 +25,9 @@ class JsonReader(JsonHandler, FileReader):
 class JsonWriter(JsonHandler, FileWriter):
     @ContextProcessor
     def envelope(self, context, fs, file, lineno):
-        file.write('[\n')
+        file.write(self.prefix)
         yield
-        file.write('\n]')
+        file.write(self.suffix)
 
     def write(self, fs, file, lineno, row):
         """