add lister sources

sessions/python-13.md

@@ -252,7 +252,7 @@ On peut le voir si on utilise des parenthèses:
 >>> generator
 <generator object <genexpr> at 0x7f654c272138>
 >>> list(generator)
-[1, 2, 3]
+[0, 1, 2]
 ```
 
 Les générateurs sont "feignants": ils ne calculent leur valeurs que quand
@@ -263,7 +263,7 @@ c'est demandé
 ```python
 >>> generator =  (x for x in range(0, 3))
 >>> list(generator)
-[1, 2, 3]
+[0, 1, 2]
 >>> list(generator)
 []
 ```

sources/lister/lister.py

@@ -0,0 +1,42 @@
+import sys
+import os
+
+def parse_args(args):
+    options = Options()
+    if "-l" in args:
+        options.show_modification_time= True
+    return options
+
+class Options:
+    def __init__(self):
+        self.show_modification_time = False
+
+class Entry:
+    def __init__(self,name):
+        self.name=name
+        self.is_directory=False
+        self.mtime=0
+        
+def get_entries():
+    names = os.listdir(".")
+    for name in names:
+        entry = Entry(name)
+        entry.mtime = os.stat(name).st_mtime
+        yield entry
+
+def list_entries(entries,options):
+    for entry in entries:
+        if options.show_modification_time :
+            yield f"{entry.name} {entry.mtime}"
+        else:
+            yield entry.name
+            
+def main():
+    options=parse_args(sys.argv)
+    entries = get_entries()
+    lines = list_entries(entries,options) 
+    for line in lines:
+        print(line)
+        
+if __name__=="__main__":
+    main()

sources/lister/test_lister.py

@@ -0,0 +1,31 @@
+import lister
+
+def test_parse_args_empty_list():
+    options = lister.parse_args([])
+    assert options.show_modification_time is False
+    
+def test_parse_args_dash_l():
+    options = lister.parse_args(["-l"])
+    assert options.show_modification_time is True
+    
+    
+def test_list_empty_entries():
+    options = lister.Options()
+    assert list(lister.list_entries([], options)) == []
+    
+
+def get_listing(entries, show_modification_time=False):
+    options = lister.Options()
+    options.show_modification_time = show_modification_time
+    return list(lister.list_entries(entries, options))
+
+def test_list_names():
+    foo_txt = lister.Entry("foo.txt")
+    entries = [foo_txt]
+    assert get_listing(entries, show_modification_time=False) == ["foo.txt"]
+    
+def test_list_mtimes():
+    foo_txt = lister.Entry("foo.txt")
+    foo_txt.mtime = 1559404640
+    entries = [foo_txt]
+    assert get_listing(entries, show_modification_time=True)== ["foo.txt 1559404640"]