file.flush

src/runtime/file.cpp

@@ -94,8 +94,7 @@ Box* fileWrite(BoxedFile* self, Box* val) {
     assert(self->cls == file_cls);
 
     if (self->closed) {
-        fprintf(stderr, "IOError: file is closed\n");
-        raiseExcHelper(IOError, "");
+        raiseExcHelper(IOError, "file is closed");
     }
 
 
@@ -129,6 +128,16 @@ Box* fileWrite(BoxedFile* self, Box* val) {
     }
 }
 
+Box* fileFlush(BoxedFile* self) {
+    RELEASE_ASSERT(self->cls == file_cls, "");
+
+    if (self->closed)
+        raiseExcHelper(IOError, "file is closed");
+
+    fflush(self->f);
+    return None;
+}
+
 Box* fileClose(BoxedFile* self) {
     assert(self->cls == file_cls);
     if (self->closed) {
@@ -199,6 +208,7 @@ void setupFile() {
     CLFunction* readline = boxRTFunction((void*)fileReadline1, STR, 1);
     file_cls->giveAttr("readline", new BoxedFunction(readline));
 
+    file_cls->giveAttr("flush", new BoxedFunction(boxRTFunction((void*)fileFlush, NONE, 1)));
     file_cls->giveAttr("write", new BoxedFunction(boxRTFunction((void*)fileWrite, NONE, 2)));
     file_cls->giveAttr("close", new BoxedFunction(boxRTFunction((void*)fileClose, NONE, 1)));
 

test/tests/file.py

@@ -34,7 +34,7 @@ f = open('/dev/null')
 print iter(f) is f
 f.close()
 
-with open('../README.md') as f:
+with open('README.md') as f:
     lines = list(f)
     print lines[:5]
     print lines[-5:]
@@ -44,3 +44,8 @@ try:
    f = open('this-should-definitely-not-exist.txt')
 except IOError as e:
    print str(e)
+
+f = open("/dev/null", "w")
+f.write("hello world")
+print f.flush()
+f.close()