Commit 461cac77 authored by Hans Fugal's avatar Hans Fugal Committed by Viswanath Sivakumar

Koans to the Future

Summary:
The first file of Koans. Some simple constructor and `makeFuture` stuff, but this diff is mostly about the framework (ie the `TARGETS` and `main.cpp` and `Koan.h`, and the layout of the Koan files).

Known Issues: I am not nearly enlightened enough to write these in a particularly zen style with lots of inside zen-jokes, so I'm not even trying.

Test Plan:
Work through the koans,
then `fbmake runtests`,
reach enlightenment

Reviewed By: davejwatson@fb.com

Subscribers: cgthayer, exa, folly-diffs@, jsedgwick, yfeldblum, bmatheny, chalfant

FB internal diff: D2082141

Tasks: 6973057

Signature: t1:2082141:1432057657:273708f566154cc54f726b85f05457388357ef4e
parent 2a919488
/*
* Copyright 2015 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "Koan.h"
#include <folly/futures/Future.h>
using folly::Future;
using folly::makeFuture;
#if 0 // compilation cursor
TEST(Values, canonicalForm) {
// The canonical way to make a Future from an immediate value is with the
// Future constructor.
Future<int> answer(__);
EXPECT_EQ(42, answer.get());
}
TEST(Values, typeDeduction) {
// If you use makeFuture, the compiler will deduce the type.
auto answer = makeFuture(__);
EXPECT_EQ(42, answer.get());
}
TEST(Values, exceptionNeedsType) {
// To create a Future holding an exception, you must
// use makeFuture with the type
std::runtime_error err("Don't Panic");
auto question = __(err);
// not
//auto question = makeFuture(err);
EXPECT_THROW(question.get(), std::runtime_error);
}
TEST(Values, typeConversion) {
// Sometimes it's cleaner to give the type and let the compiler do implicit
// type conversion
__ answer(42);
// not
//auto answer = makeFuture((double)42);
EXPECT_EQ(__, answer.get());
}
using folly::Try;
TEST(Values, tryInside) {
// Futures hold either a Value or Exception. This is accomplished under the
// covers with Try
Try<int> t = makeFuture(42).__();
EXPECT_TRUE(t.hasValue());
EXPECT_EQ(42, t.value());
t = Future<int>(std::runtime_error("Don't Panic")).__();
EXPECT_TRUE(t.hasException());
EXPECT_THROW(t.value(), std::runtime_error);
}
#endif
/*
* Copyright 2015 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <folly/Portability.h>
#include <gtest/gtest.h>
#include <gflags/gflags.h>
Working through [Programming Koans][1] can be a fun, lightweight, and fast way to
learn a new language or pattern with small, focused exercises. Therefore, we
present Koans for Futures. Perhaps you will call them "Koans to Be".
Edit the topical files one at a time, moving the "compilation cursor" down one
exercise at a time, and getting them to pass by filling in the blanks.
[1] http://www.lauradhamilton.com/learn-a-new-programming-language-today-with-koans
[2] http://catb.org/esr/writings/unix-koans/ten-thousand.html
/*
* Copyright 2015 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "Koan.h"
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
::gflags::ParseCommandLineFlags(&argc, &argv, true);
return RUN_ALL_TESTS();
}
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