Quotes About Change

Gather together those things that change at the same times and for the same reasons. Separate those things that change at different times or for different reasons.

Part of the art of developing a software architecture is carefully separating those policies from one another, and regrouping them based on the ways that they change.

Policies that change for the same reasons, and at the same times, are at the same level and belong together in the same component. Policies that change for different reasons, or at different times, are at different levels and should be separated into different components.

Architects separate functionality based on how, why, and when it changes, and then organize that separated functionality into a hierarchy of components.

The OCP is one of the driving forces behind the architecture of systems. The goal is to make the system easy to extend without incurring a high impact of change. This goal is accomplished by partitioning the system into components, and arranging those components into a dependency hierarchy that protects higher-level components from changes in lower-level components.

One sure way to make a software component difficult to change, is to make lots of other software components depend on it.

The diagram in Figure 14.5 shows X, which is a stable component. Three components depend on X, so it has three good reasons not to change. We say that X is responsible to those three components. Conversely, X depends on nothing, so it has no external influence to make it change. We say it is independent.

Figure 14.6 shows Y, which is a very unstable component. No other components depend on Y, so we say that it is irresponsible. Y also has three components that it depends on, so changes may come from three external sources. We say that Y is dependent.

When the stakeholders change their minds about a feature, that change should be simple and easy to make. The difficulty in making such a change should be proportional only to the scope of the change, and not to the shape of the change.

When the I metric is 1, it means that no other component depends on this component (Ca = 0), and this component does depend on other components (Ce > 0). This is as instable as a component can get; it is irresponsible and dependent. Its lack of dependents gives it no reason not to change, and the components that it depends on may give it ample reason to change.

there's no such thing as a program that is impossible to change. However, there are systems that are practically impossible to change, because the cost of change exceeds the benefit of change. Many systems reach that point in some of their features or configurations.

highway through the middle of a small town that anticipates growth? Who would want such a road through their town? It is a myth that we can get systems "right the first time." Instead, we should implement only today's stories, then refactor and expand the system to implement new stories tomorrow.

Don't depend on volatile things. GUIs are volatile.

Why do most developers fear to make continuous changes to their code? They are afraid they'll break it! Why are they afraid they'll break it? Because they don't have tests.

Perhaps you thought that "getting it working" was the first order of business for a professional developer. I hope by now, however, that this book has disabused you of that idea. The functionality that you create today has a good chance of changing in the next release, but the readability of your code will have a profound effect on all the changes that will ever be made.

The real point is this: We don't know where to go because we don't know what we are. Do you want to go back to living in a sewer-pipe? And eating other people's garbage? Because that's what rats do. But the fact is, we aren't rats anymore. We are something Dr. Schultz has made. Something new.

I say, why start from nothing if you can start with everything? We've already got a civilization.' 'No. We haven't. We're just living on the edge of someone else's, like fleas on a dog's back. If the dog drowns, the fleas drown, too.

One of these days, one of these years, the tree will fall, and when it does, if I am still alive, I will fall with it.

I want to emphasize the second Hegel, the Heraclitan Hegel, the Hegel of endless change, and what he calls "the bad infinity," running on without end. This is the Hegel who said, in effect, that there is no unity except through differences and there is no end to philosophy.

comes into the world proclaiming the need for and possibility of profound change.

Such movements typically attract persons who are experiencing some form of acute distress—social, economic, psychic, or a combination of these—and who respond eagerly to the promise of deliverance from it. An individual in whom this promise appears to be embodied, whether by virtue of his coming forward with a gospel of radical change or his ability to show the way to change, is a candidate for the role of charismatic leader.

It had taken about two centuries for the feudal system of economy to show its superiority over the slave system, Stalin said, and about a hundred years or less for the bourgeois system to prove its superiority over feudal economy. Because technological progress had now greatly accelerated the pace of development and change, however, the socialist system of economy could advance with "giant strides" and out-perform capitalism in a much shorter period.

The socialist doctrines that appeared in the first half of the nineteenth century, Marxism included, were gospels of radical change addressed to the alleviation of this misery. Friedrich Engels himself was one of the first to point out the resemblance between this historical situation and that in which Christianity arose.

Where to Begin?" Printed in Stuttgart in March 1902, under the title What Is to Be Done? Burning Questions of Our Movement,